Interstate 70 in Colorado

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Interstate 70 marker
Interstate 70
I-70 highlighted in red
Route information
Maintained by CDOT
Length449.589 mi[1] (723.543 km)
HistoryDesignated in 1956
Completed in 1992
RestrictionsNo hazardous goods allowed in the Eisenhower Tunnel
Major junctions
West end I-70 / US 6 / US 50 at Utah state line
East end I-70 / US-24 at Kansas state line
CountiesMesa, Garfield, Eagle, Summit, Clear Creek, Jefferson, Denver, Adams, Arapahoe, Elbert, Lincoln, Kit Carson
Highway system
Colorado State Highways
SH 69 SH 71

Interstate 70 (I-70) is a transcontinental Interstate Highway in the United States, stretching from Cove Fort, Utah, to Baltimore, Maryland. In Colorado, the highway traverses an east–west route across the center of the state. In western Colorado, the highway connects the metropolitan areas of Grand Junction and Denver via a route through the Rocky Mountains. In eastern Colorado, the highway crosses the Great Plains, connecting Denver with metropolitan areas in Kansas and Missouri. Bicycles and other non-motorized vehicles, normally prohibited on Interstate Highways, are allowed on those stretches of I-70 in the Rockies where no other through route exists.

The United States Department of Transportation (USDOT) lists the construction of I-70 among the engineering marvels undertaken in the Interstate Highway system, and cites four major accomplishments: the section through the Dakota Hogback, Eisenhower Tunnel, Vail Pass and Glenwood Canyon. The Eisenhower Tunnel, with a maximum elevation of 11,158 feet (3,401 m) and length of 1.7 miles (2.7 km), is the longest mountain tunnel and highest point along the Interstate Highway System. The portion through Glenwood Canyon was completed on October 14, 1992. This was one of the final pieces of the Interstate Highway System to open to traffic, and is one of the most expensive rural highways per mile built in the United States. The Colorado Department of Transportation (CDOT) earned the 1993 Outstanding Civil Engineering Achievement Award from the American Society of Civil Engineers for the completion of I-70 through the canyon.

When the Interstate Highway system was in the planning stages, the western terminus of I-70 was proposed to be at Denver. The portion west of Denver was included into the plans after lobbying by Governor Edwin C. Johnson, for whom one of the tunnels along I-70 is named. East of Idaho Springs, I-70 was built along the corridor of U.S. Highway 40, one of the original transcontinental U.S. Highways. West of Idaho Springs, I-70 was built along the route of U.S. Highway 6, which was extended into Colorado during the 1930s.

Route description[edit]

A railroad, river and two-tiered highway following a narrow canyon
Westbound I-70 on a viaduct inside Glenwood Canyon paralleling the Colorado River and former Denver and Rio Grande Western Railroad (now Union Pacific) main line

Colorado River[edit]

I-70 enters Colorado from Utah, concurrent with US 6 and US 50, on a plateau between the north rim of Ruby Canyon of the Colorado River and the south rim of the Book Cliffs. The plateau ends just past the state line and the highway descends into the Grand Valley, formed by the Colorado River and its tributaries.[2] The Grand Valley is home to several towns and small cities that form the Grand Junction Metropolitan Statistical Area, the largest conurbation in the area regionally known as the Western Slope. The highway directly serves the communities of Fruita, Grand Junction and Palisade. Grand Junction is the largest city between Denver and Salt Lake City and serves as the economic hub of the area.[3] The freeway passes to the north of downtown, while US 6 and 50 retain their original routes through downtown. US 6 rejoins I-70 east of Grand Junction; US 50 departs on a course toward Pueblo.[2]

I-70 exits the valley through De Beque Canyon, a path carved by the Colorado River that separates the Book Cliffs from Battlement Mesa. The river and its tributaries provide the course for the ascent up the Rocky Mountains. In the canyon, I-70 enters the Beavertail Mountain Tunnel, the first of several tunnels built to route the freeway across the Rockies. This tunnel design features a curved sidewall, unusual for tunnels in the United States, where most tunnels feature a curved roof and flat side-walls. Engineers borrowed a European design to give the tunnel added strength.[4] After the canyon winds past the Book Cliffs, the highway follows the Colorado River through a valley containing the communities of Parachute and Rifle.[2]

Glenwood Canyon[edit]

East of the city of Glenwood Springs, the highway enters Glenwood Canyon. Both the federal and state departments of transportation have praised the engineering achievement required to build the freeway through the narrow gorge while preserving the natural beauty of the canyon.[4][5] A 12-mile (19 km) section of roadway features the No Name Tunnel, Hanging Lake Tunnel, Reverse Curve Tunnel, 40 bridges and viaducts, and miles of retaining walls.[6] Through a significant portion of the canyon, the eastbound lanes extend cantilevered over the Colorado River and the westbound lanes are suspended on a viaduct several feet above the canyon floor.[5][7] Along this run, the freeway hugs the north bank of the Colorado River, while the main line of the Union Pacific Railroad (formerly the Denver and Rio Grande Western) occupies the south bank.[2]

A pair of bridges leading to a pair of tunnels at the canyon wall
The western portal of the Hanging Lake Tunnel; at this point in the canyon both the river and the railroad are directly below the freeway viaducts.

To minimize the hazards along this portion, a command center staffed with emergency response vehicles and tow trucks on standby monitors cameras along the tunnels and viaducts in the canyon. Traffic signals have been placed at strategic locations to stop traffic in the event of an accident, and variable message signs equipped with radar guns will automatically warn motorists exceeding the design speed of one of the curves.[8] The USDOT makes provision for bicycles, which are usually prohibited along Interstate Highways, along the freeway corridor in Glenwood Canyon.[9] After the 2020 Grizzly Creek Fire, I-70 was closed in Glenwood Canyon in August 2021 due to significant damage by debris from the fire, causing large detours.[10]

Rocky Mountains[edit]

The highway departs the Colorado River near Dotsero, the name given to the railroad separation for the two primary mountain crossings, the original via Tennessee Pass/Royal Gorge and the newer and shorter Moffat Tunnel route.[11] I-70 uses a separate route between the two rail corridors. From this junction I-70 follows the Eagle River toward Vail Pass, at an elevation of 10,666 feet (3,251 m). In this canyon I-70 reaches the western terminus of U.S. Highway 24, which meanders through the Rockies before rejoining I-70. US 24 is known as the Highway of the Fourteeners, from the concentration of mountains exceeding 14,000 feet (4,300 m) along the highway corridor.[12] Along the ascent, I-70 serves the ski resort town of Vail and the ski areas of Beaver Creek Resort, Vail Ski Resort and Copper Mountain.[2]

Automobiles are driving on a road leading to one of two openings in a building against a mountain. Letters above each opening read "Johnson Tunnel 1979" and "Eisenhower Tunnel 1973". On the roof of the building, large ventilation hoods are visible.
Entrance to the Eisenhower Tunnel

The construction of the freeway over Vail Pass is also listed as an engineering marvel. One of the challenges of this portion is the management of the wildlife that roams this area. Several parts of the approach to the pass feature large fences that prevent wildlife from crossing the freeway and direct the animals to one of several underpasses. At least one underpass is located along a natural migratory path and has been landscaped to encourage deer to cross.[1][13]

The highway descends to Dillon Reservoir, near the town of Frisco, and begins one final ascent to the Eisenhower Tunnel, where the freeway crosses the Continental Divide. At the time of dedication, this tunnel was the highest vehicular tunnel in the world, at 11,158 feet (3,401 m).[14] As of 2010, the facility was still the highest vehicular tunnel in the United States.[6] The Eisenhower Tunnel is noted as both the longest mountain tunnel and the highest point on the Interstate Highway System.[14] The tunnel has a command center, staffed with 52 full-time employees, to monitor traffic, remove stranded vehicles, and maintain generators to keep the tunnel's lighting and ventilation systems running in the event of a power failure. Signals are placed at each entrance and at various points inside the tunnel to close lanes or stop traffic in an emergency.[14] There are several active and former ski resorts in the vicinity of the tunnel, including Breckenridge Ski Resort, Keystone Resort, Arapahoe Basin, Loveland Ski Area, Berthoud Pass Ski Area and Winter Park Resort.[2]

Clear Creek[edit]

The freeway follows Clear Creek down the eastern side of the Rockies, passing through the Veterans Memorial Tunnels[15] near Idaho Springs. Farther to the east, I-70 departs the US 6 corridor, which continues to follow Clear Creek through a narrow, curving gorge. The interstate, however, follows the corridor of US 40 out of the canyon. The highway crests a small mountain near Genesee Park to descend into Mount Vernon Canyon to exit the Rocky Mountains.[2] This portion features grade-warning signs with unusual messages, such as "Trucks: Don't be fooled," "Truckers, you are not down yet," and "Are your brakes adjusted and cool?"[16] Runaway truck ramps are a prominent feature along this portion of I-70,[4] with a total of seven used along the descent of either side the Continental Divide to stop trucks with failed brakes.[1]

A highway near the top of a ridge. On either side of the highway are big yellow signs reading, "Trucks, Don't be Fooled – 4 more miles of steep grades and sharp curves".
Warning sign stating, "Trucks, Don't be Fooled – 4 more miles of steep grades and sharp curves."

The last geographic feature of the Rocky Mountains traversed before the highway reaches the Great Plains is the Dakota Hogback. The path through the hogback features a massive cut that exposes various layers of rock millions of years old. The site includes a nature study area for visitors.[4][17]

Great Plains[edit]

As the freeway passes from the Rocky Mountains to the Great Plains, I-70 enters the Denver metropolitan area, part of a larger urban area called the Front Range Urban Corridor. The freeway arcs around the northern edge of the LoDo district, the common name of the lower downtown area of Denver. Through the downtown area, US 40 is routed along Colfax Avenue, which served as the primary east–west artery through the Denver area before the construction of I-70. Through downtown, US 6 is routed along 6th Avenue before departing the I-70 corridor to join Interstate 76 on a northeast course toward Nebraska.[2] The freeway meets Interstate 25 in an interchange frequently called the Mousetrap.[4] From I-25 on to I-225, I-70 serves – together with those two Interstates – as part of an inner beltway around Denver.[18]

A six-lane freeway in a developed area with mountains in the distance.
I-70 westbound at the US 287 interchange in Denver

I-70 has one official branch in Colorado, Interstate 270, which connects the interstate with the Denver–Boulder Turnpike. Where these two freeways merge is the busiest portion of I-70 in the state, with an annual average daily traffic of 183,000 vehicles per day as of 2009.[19] While State Highway 470 and E-470 are not officially branches of I-70, they are remnants of plans for an I-470 outer beltway around Denver that were cancelled when the allocated funds were spent elsewhere.[20]

Leaving Denver, the highway serves the redevelopment areas on the former site of Stapleton International Airport; runway 17R/35L crossed over the Interstate at the runway's midsection.[2] East of Aurora, I-70 rejoins the alignment of U.S. Highway 40 at Colfax Avenue. The freeway proceeds east across the Great Plains, briefly dipping south to serve the city of Limon, which bills itself as Hub City because of the many rail and road arteries that intersect there.[21] I-70 enters Kansas near Burlington, a small community known for having one of the oldest carousels in the United States.[22]


As first proposed in 1944, the western terminus of I-70 was Denver, along the corridor of US 40. The portion across the Rocky Mountains was added to the plans, after lobbying by Colorado officials, following the US 6 corridor.[13] The origins of both the US 40 and US 6 pre-date the U.S. System of numbered highways, using established transcontinental trails.[23]

Earlier routes[edit]

Before the formation of the United States Numbered Highways, the U.S. relied on an informal network of roads, organized by various competing interests, collectively called the auto trail system. The surveyors of most trails chose either South Pass in Wyoming or a southern route through New Mexico to traverse the Rocky Mountains. Both options were less formidable than the higher mountain passes in Colorado, but left the state without a transcontinental artery. When the planners of the Lincoln Highway also decided to cross the Rockies in Wyoming, officials pressed for a loop to branch from the main route in Nebraska, enter Colorado, and return to the main route in Wyoming. While the Lincoln Highway was briefly routed this way, the loop proved impractical and was soon removed.[23]

A highway about to curve to the right while descending down a canyon
I-70 crossing the Rocky Mountains

After losing the connection to the Lincoln Highway, officials convinced planners of the Victory Highway to traverse the state. The highway entered Colorado from Kansas along what was previously called the Smoky Hill Trail. The highway crossed the mountains along a trail blazed by a railroad surveyor and captain in the American Civil War, cresting at Berthoud Pass.[23] After a round of political infighting between Utah and Nevada, the Victory Highway would become the Lincoln Highway's main rival for San Francisco-bound traffic.[24] When the U.S. Highway system was unveiled in 1926, the Victory Highway was numbered U.S. Highway 40.[23]

While US 6 was also one of the original 1926 U.S. Highways, the road originally served the portion of the United States east of the Rocky Mountains. The highway was not extended to the Pacific coast until 1937, mostly following the Midland Trail.[25] Around the time the U.S. Highway system was formed, the portion of the Midland Trail through Glenwood Canyon, known as the Taylor State Road, was destroyed by a flood.[23] When US 6 was extended, the Works Progress Administration was rebuilding the road through the canyon and the Public Works Administration was nearing completion of a new highway over Vail Pass.[13][23] In western Colorado, US 6 was routed concurrent with US 50 from the Utah state line to Grand Junction and eventually replaced US 24 from Grand Junction to near Vail.[26] To keep these routes over the Rockies competitive with alternatives in other states, the Colorado Department of Highways relied on ingenuity to keep the roads safe. The department pioneered new machines to clear snow and various bridge and culvert designs to protect the roads from flooding.[23]

Interstate Highway planning[edit]

A sharp curve with a cut in the mountain visible to support the highway
Interstate 70 descending into Clear Creek Canyon

Governor Edwin C. Johnson, for whom one of the tunnels along I-70 was later named, was a primary force in persuading the planners of the Interstate Highway System to extend the highway across the state. He stated to the Senate subcommittee in 1955:

You are going to have a four-lane highway through Wyoming. You are going to build two four-lane highways through New Mexico and Arizona. Colorado needs to be able to compete with our neighboring states. We do not want to take anything away from them. We do not want them to get way out ahead of us, either, because these interstate highways are going to be very attractive highways for the East and West to travel on.[13]

Colorado held several meetings to convince reluctant Utah officials they would benefit from a freeway link between Denver and Salt Lake City. Utah officials expressed concerns that, given the terrain between these cities, this link would be difficult to build. They later expressed concerns that the construction would drain resources from completing Interstate Highways they deemed to have a higher priority. Colorado officials persisted, presenting three alternatives to route I-70 west of Denver, using the corridors of US 40, US 6 and a route starting at Pueblo, proceeding west along US 50/US 285/US 24. In March 1955, Colorado officials succeeded in convincing Utah officials with the state legislature passing a resolution supporting a link with Denver. The two states jointly issued a proposal to the U.S. Congress that would extend the plans for I-70 along the US 6 corridor. Under this proposal the freeway would terminate at I-15 near Spanish Fork, Utah, linking the Front Range and Wasatch Front metropolitan areas.[13]

Beavertail Mountain tunnel as seen from Amtrak's California Zephyr

Congress approved the extension of I-70; however, the route still had to be approved by the representatives of the U.S. military on the planning committee. Military representatives were concerned that plans for this new highway network did not have a direct connection from the central U.S. to southern California; and further felt Salt Lake City was adequately connected. Military planners approved the extension, but moved the western terminus south to Cove Fort, using I-70 as part of a link between Denver with Los Angeles instead of Salt Lake City. Utah officials objected to the modification, complaining they were being asked to build a long and expensive freeway that would serve no populated areas of the state. After being told this was the only way the military would approve the extension, Utah officials agreed to build the freeway along the approved route.[13]


Several mountains with scars from roads visible at the base and up the sides
View from Loveland Pass, showing a hairpin turn along the US 6 alignment on top right, and the straighter I-70 emerging from the Eisenhower Tunnel on the left

The first Colorado portion of I-70 opened to traffic in 1961. This section bypassed and linked Idaho Springs to the junction where US 6 currently separates from I-70 west of the city. The majority of the alignment through Denver was completed by 1964. The Mousetrap reused some structures that were built in 1951, before the formation of the Interstate Highway system. The last piece east of Denver opened to traffic in 1977.[4]

Eisenhower Tunnel[edit]

Planning on how to route the freeway over the Rocky Mountains began in the early 1960s. The US 6 corridor crosses two passes: Loveland Pass, at an elevation of 11,992 feet (3,655 m) and Vail Pass, at 10,666 feet (3,251 m).[2] Engineers recommended tunneling under Loveland Pass to bypass the steep grades and hairpin curves required to navigate US 6. The project was originally called the Straight Creek Tunnel, after the waterway that runs along the western approach. The tunnel was later renamed the Eisenhower–Johnson Memorial Tunnel, after U.S. President Dwight D. Eisenhower and Colorado Governor Edwin C. Johnson.[14]

Construction on the first bore of the tunnel was started on March 15, 1968.[14] Construction efforts suffered many setbacks and the project went well over time and budget. One of the biggest setbacks was the discovery of fault lines in the path of the tunnel that were not discovered during the pilot bores.[27] These faults began to slip during construction and emergency measures had to be taken to protect the tunnels and workers from cave-ins and collapses.[23] A total of nine workers were killed during the construction of both bores. Further complicating construction was that the boring machines could not work as fast as expected at such high altitudes, and the productivity was significantly less than planned. The frustration prompted one engineer to comment, "We were going by the book, but the damned mountain couldn't read."[27] The first bore was dedicated March 8, 1973. Initially this tunnel was used for two-way traffic, with one lane for each direction. The amount of traffic through the tunnel exceeded predictions, and efforts soon began to expedite construction on the second tube (the Johnson bore), which was finished on December 21, 1979.[14] The initial engineering cost estimate for the Eisenhower bore was $42 million; the actual cost was $108 million (equivalent to $484 million in 2019[28]). Approximately 90% of the funds were paid by the federal government, with the state of Colorado paying the rest. At the time, this figure set a record for the most expensive federally aided project. The excavation cost for the Johnson bore was $102.8 million (equivalent to $367 million in 2019[28]).[27][29]

A parking lot with a view of several snow-capped mountains
Rest area along I-70 at the top of Vail Pass

The tunnel construction became involved in the women's rights movement due to advocacy by Janet Bonnema after she was subjected to gender-based discrimination after being hired as an engineering technician for the construction of the Straight Creek Tunnel in 1970. Bonnema was restricted from entering the tunnel due to the miners' superstition that women who entered underground mines and tunnels would bring bad luck. In 1972, Bonnema filed a $100,000 class action suit against the Colorado Department of Transportation, citing Title VII of the Civil Rights Act of 1964. As Colorado voters had passed the Equal Rights Amendment that year, the state settled Bonnema's case out of court for $6,730. Bonnema entered the tunnel for the first time on November 9, 1972, prompting 66 workers to temporarily walk off the job; most returned the next day. She continued with the project until the tunnel opened.[30]

Vail Pass[edit]

While designing the Eisenhower Tunnel, controversies erupted over how to build the portions over Vail Pass and Glenwood Canyon. The route of US 6 over Vail Pass has a distinctive "V" shape. Initially, engineers thought they could shorten the route of I-70 by about 10 miles (16 km) by tunneling from Gore Creek to South Willow Creek, an alternative known as the Red Buffalo Tunnel.[23] This alternative sparked a nationwide controversy as it would require an easement across federally protected lands, through what is now called the Eagles Nest Wilderness. After the U.S. Secretary of Agriculture refused to grant the easement, the engineers agreed to follow the existing route across Vail Pass. The engineers added infrastructure to accommodate wildlife, and had significant portions of the viaducts constructed offsite and lifted in place to minimize the environmental footprint.[23] The grade over Vail Pass reaches seven percent.[31]

Glenwood Canyon[edit]

A two tiered highway snaking around bends in a canyon, with some fall foliage visible
I-70 in Glenwood Canyon as seen from Amtrak's California Zephyr

Glenwood Canyon has served as the primary transportation artery through the Rocky Mountains, even before the creation of U.S. highways. Railroads have used the canyon since 1887 and a dirt road was built through the canyon in the early 20th century.[8] The first paved road was built from 1936 to 1938 at a cost of $1.5 million (equivalent to $21.8 million in 2019[28]).[23]

With the Eisenhower Tunnel finished, the last remaining obstacle for I-70 to be an interstate commercial artery was the two lane, non-freeway portion in Glenwood Canyon. Construction had started on this section in the 1960s with a small section opening to traffic in 1966.[4] The remainder was stopped due to environmentalist protests that caused a 30-year controversy.[13] The original design was criticized as "the epitome of environmental insensitivity". Engineers scrapped the original plans and started work on a new design that would minimize additional environmental impacts.[32] A new design was underway by 1971, which was approved in 1975; however, environmental groups filed lawsuits to stop construction, and the controversy continued even when construction finally resumed in 1981.[23] The final design included 40 bridges and viaducts, three additional tunnel bores (two were completed before construction was stopped in the 1960s) and 15 miles (24 km) of retaining walls for a stretch of freeway 12 miles (19 km) long.[6] The project was further complicated by the need to build the four-lane freeway without disturbing the operations of the railroad. This required using special and coordinated blasting techniques.[33] Engineers designed two separate tracks for the highway, one elevated above the other, to minimize the footprint in the canyon.[8] The final design was praised for its environmental sensitivity. A Denver architect who helped design the freeway proclaimed, "Most of the people in western Colorado see it as having preserved the canyon." He further stated, "I think pieces of the highway elevate to the standard of public art."[32] A portion of the project included shoring up the banks of the Colorado River to repair damage and remove flow restrictions created in the initial construction of US 6 in the 1930s.[34]

Diagram showing the former profile of a canyon wall with a new profile showing re-graded slopes, re-graded riverbank, medians and a two-tiered highway. The tops of the highway cantilever over the retaining wall, to hide the infrastructure below.
Department of Transportation drawing showing how re-using the existing footprint of US 6 combined with elevating two lanes helped minimize the environmental impact of the freeway on Glenwood Canyon

The freeway was finally completed on October 14, 1992, in a ceremony covered nationwide.[35][36] Most coverage celebrated the engineering achievement or noted this was the last major piece of the Interstate Highway System to open to traffic. However, newspapers in western Colorado celebrated the end of the frustrating traffic delays. For most of the final 10 years of construction, only a single lane of traffic that reversed direction every 30 minutes remained open in the canyon. One newspaper proudly proclaimed "You heard right. For the first time in more than 10 years, construction delays along that 12-mile (19 km) stretch of Interstate 70 will be non-existent."[37]

The cost was $490 million (equivalent to $818 million in 2019[28]) to build 12 miles (19 km), 40 times the average cost per mile predicted by the planners of the Interstate Highway system.[23] This figure exceeded that of Interstate 15 through the Virgin River Gorge, which was previously proclaimed the most expensive rural freeway in the United States.[38] The construction of I-70 through Glenwood Canyon earned 30 awards for the Colorado Department of Transportation,[8] including the 1993 Outstanding Civil Engineering Achievement Award from the American Society of Civil Engineers.[39] At the dedication it was claimed that I-70 through Glenwood Canyon was the final piece of the Interstate Highway System to open to traffic. For this reason, the system was proclaimed to be complete.[6][8] However, at the time there were still two sections of the original Interstate Highway System that had not been constructed: a section of Interstate 95 in central New Jersey,[40] that was not completed until 2018[41] and a section of I-70 in Breezewood, Pennsylvania.[42]

The damage after the 2021 landslides requires lengthy reconstruction of the road, and the first $11.6 million in federal emergency relief funding was approved (of $116 million requested). Partial re-opening was estimated at days to weeks. The highway partially reopened on August 14, 2021.[43][44][45]


When first approved, the extension of I-70 from Denver to Cove Fort was criticized in some area newspapers as a road to nowhere;[46] an information liaison specialist with the U.S. Department of Transportation in Baltimore, Maryland – the eastern terminus of I-70 – claims people have asked "did we think Baltimoreans were so desperate to get to Cove Fort that we were willing to pay $4 billion to get them there?"[13] However, a resident engineer with the USDOT has called the extension one of the "crown jewels" of the Interstate Highway System.[8] In Colorado, the freeway helped unite the state, despite the two halves being separated by the formidable Rocky Mountains. The Eisenhower Tunnel alone is credited with saving up to an hour from the drive across the state.[23] Prior to I-70's construction, the highway through Glenwood Canyon was one of the most dangerous in the state. With the improvements, the accident rate has dropped 40% even though traffic through the canyon has substantially increased.[8] The Colorado Department of Transportation is considering the nomination of various portions of I-70 as a National Historic Landmark, even though the freeway will not qualify as historical for several decades.[23]

I-70 through the Colorado Plateau

The freeway is credited with enhancing Colorado's ski industry. The ski resort town of Vail did not exist until I-70 began construction, with developers working in close partnership with the Department of Transportation.[23] By 1984, the I-70 corridor between Denver and Grand Junction contained the largest concentration of ski resorts in the United States. The towns and cities along the corridor have experienced significant growth, luring recreational visitors from the Denver area. As one conservationist lamented, I-70 "changed rural Colorado into non-rural Colorado".[23]

One accident at the Mousetrap, a complex interchange, had national ramifications. On August 1, 1984, a truck carrying six torpedoes for the U.S. Navy overturned. The situation was made worse as no one answered at the phone number provided with the cargo, and an unknown liquid was leaking from one of the torpedoes. It took more than three hours before any military personnel arrived on the scene, U.S. Army personnel from a nearby base. The incident left thousands of cars stranded and Denver's transportation network paralyzed for about eight hours. Approximately 50 residents in the area were evacuated.[47][48] Investigations later revealed that the truck driver did not follow a recommended route provided by the state police, who specifically warned the driver to avoid the Mousetrap.[47] The Navy promised reforms after being criticized for providing an unstaffed phone number with a hazardous cargo shipment, a violation of federal law, and failing to notify Denver officials about the shipment.[49][50] The Mousetrap was grandfathered into the Interstate Highway system, with some structures built in 1951.[4] The incident provided momentum to rebuild the interchange with a more modern and safer design. Construction began in several phases in 1987 and the last bridge was dedicated in 2003.[51]

In 2014, mile marker 420 was altered by CDOT to read "Mile 419.99" following repeat thefts of the original sign due to the significance of the number 420 in cannabis culture.[52]


CDOT is replacing a 1.8-mile (2.9 km) viaduct that formerly carried I-70 between Brighton Boulevard and Colorado Boulevard in Denver with a below-grade highway; the project is expected to be completed in 2022. The $1.2 billion project, financed through a public–private partnership with Kiewit and Meridiam, would add a new express toll lane and build frontage roads; the below-grade freeway would have a four-acre (1.6 ha) park built over the top between Clayton and Columbine streets.[53][54] The project has attracted controversy from activists opposed to highway expansion, including lawsuits filed over changes to federal air quality standards that would allow the project to be built.[55][56]

Exit list[edit]

Mesa0.0000.000 I-70 west (US 6 / US 50 west) – SalinaContinuation into Utah
1.8142.9192Rabbit Valley
Mack11.10617.87311Mack ( US 6 / US 50 east)Eastern end of concurrency with US 6/US 50
15.08124.27115 SH 139 north – Loma, RangelySouthern terminus of SH 139
SH 340 to US 6 (US 50) – Fruita
Grand Junction25.56341.14026 I-70 BL east / US 6 / US 50 – Grand JunctionDiverging diamond interchange; Grand Junction appears only on eastbound signage
27.57044.3702824 Road
Redlands Parkway
31.35150.45531Horizon Drive
I-70 BL west to US 6 – Clifton, Delta, Grand Junction
Delta appears only on eastbound signage; US 6 and Grand Junction appear only on westbound signage
To US 6 – Palisade
US 6 appears only on eastbound signage
43.68270.29944 US 6 west – PalisadeWestbound exit and eastbound entrance; western end of concurrency with US 6
46.86775.42547James M. Robb – Colorado River State Park, Island AcresFormer port of entry
SH 65 south to SH 330 east – Grand Mesa, Collbran
50.38181.080Beavertail Tunnel
61.64899.21362De Beque (US 6 east)Eastern end of concurrency with US 6[58]
US 6 to CR 215 north – West Parachute
Dumbbell interchange; opened October 31, 2012[59]
74.661120.15575Parachute, Battlement Mesa
Rifle86.850139.77287West Rifle (US 6)
90.422145.52090 SH 13 north – Rifle, MeekerEastbound entrance ramp includes direct entrance from Airport Road
93.991151.26494Garfield County Regional Airport
Silt97.427156.79497 I-70 BS north – Silt
105.260169.400105New Castle
Chacra109.000175.418109Canyon Creek (US 6 west)Western end of concurrency with US 6
111.328179.165111South Canyon
Glenwood Springs114.295183.940114West Glenwood (US 6 east)Dumbbell interchange; eastern end of concurrency with US 6
116.380187.295116 SH 82 east (Grand Avenue) / US 6 west – Glenwood Springs, AspenPartial dumbbell interchange; western end of concurrency with US 6[60]
118.640190.933119No Name
120.954194.657121Grizzly Creek to Hanging LakeHanging Lake appears only on westbound signage
122.660197.402123ShoshoneEastbound exit and westbound entrance
125.061201.266125Hanging LakeEastbound exit and westbound entrance
125.269201.601Hanging Lake Tunnel
128.317206.506129Bair Ranch
Gypsum139.533224.557140Gypsum (US 6 east)Eastern end of concurrency with US 6
156.547251.938157 SH 131 north – Wolcott, Steamboat Springs
162.782261.972163 I-70 BS south – Edwards
168.157270.622168William J. Post Boulevard – Avon East Entrance
Eagle-Vail168.758271.590169 US 6 – Eagle-VailWestbound exit and eastbound entrance
171.105275.367171 US 6 west / US 24 east – Minturn, LeadvilleWestern end of concurrency with US 6; western terminus of US 24
Vail173.319278.930173West Vail
176.057283.336176Vail Ski Area – Vail Museum
179.866289.466180East Vail
Vail Pass189.981305.745Elevation 10,662 feet (3,250 m)
Summit190.095305.928190Shrine Pass Road – Vail Pass rest area
195.298314.302195 SH 91 south – Copper Mountain, Leadville
197.854318.415198Officers Gulch
Frisco200.995323.470201Main Street – Frisco, BreckenridgeBreckenridge appears only on eastbound signage; Main Street appears only on westbound signage
202.352325.654203 SH 9 south – Frisco, BreckenridgeWestern end of concurrency with SH 9; Breckenridge appears only on westbound signage
Silverthorne205.423330.596205 SH 9 north (Blue River Parkway) / US 6 east – Silverthorne, DillonEastern end of concurrency with US 6/SH 9
Continental Divide213.651–
Eisenhower Tunnel
Clear Creek216.185347.916216 US 6 west – Loveland PassWestern end of concurrency with US 6
218.346351.394218(no name)Connects to Herman Gulch Road[61]
Silver Plume225.719363.260226Silver Plume
231.889373.189232 US 40 west – Empire, GranbyWestern end of concurrency with US 40
233.047375.053233LawsonEastbound exit only
234.209376.923234Downieville, Dumont, LawsonDumont appears only on eastbound signage; Lawson appears only on westbound signage
235.005378.204235DumontWestbound exit and eastbound entrance
237.660382.477238Fall River Road
Idaho Springs238.704–
239 I-70 BL east – Idaho SpringsNo eastbound entrance; I-70 Bus. appears only on eastbound signage
239.652385.683240 SH 103 / Mount Evans Scenic Byway – Mt. Evans
241.125388.053241 I-70 BL west – Idaho SpringsI-70 Bus. appears only on westbound signage
242.292389.931Veterans Memorial Tunnels[15]
242.980391.038243Hidden Valley, Central City
244.260393.098244 US 6 / US 40 east – GoldenLeft exit eastbound; left entrance westbound; no eastbound entrance; eastern end of concurrency with US 6/US 40
246.602396.867247Beaver Brook, Floyd HillEastbound exit and westbound entrance
Jefferson247.604398.480248Westbound exit and eastbound entrance
250.769403.574251El RanchoEastbound exit and westbound entrance
251.318404.457252 SH 74 (Evergreen Parkway) / US 40 westWestbound exit and eastbound entrance; western end of concurrency with US 40
252.244405.947253Chief Hosa
253.528408.014254 US 40 east – Genesee ParkEastern end of concurrency with US 40
255.974411.950256Lookout Mountain
258.722416.373259 US 40 east – Golden, MorrisonEastbound signage
CR 93 – MorrisonWestbound signage
Golden259.803418.112260 SH 470 – Boulder, Colorado SpringsSH 470 exit 1; no westbound exit or eastbound entrance from SH 470 EB
261.030420.087261 US 6 east (6th Avenue)Eastbound exit and westbound entrance
US 40 / I-70 BL (Colfax Avenue) to US 6
I-70 Bus. appears only on eastbound signage; US 6 appears only on westbound signage
Lakewood262.571422.567263Colorado Mills Parkway – Denver West
Wheat Ridge264.341425.416264Youngfield Street/32nd Avenue
265.343427.028265 SH 58 west – Golden, Central City
265.726427.645266 SH 72 (Ward Road) / 44th Avenue
267.402430.342267 SH 391 (Kipling Street)
Arvada269.005432.922269A SH 121 (Wadsworth Boulevard)
269.242433.303269B I-76 east – Fort MorganEastbound left exit and westbound entrance; western terminus of I-76
Wheat RidgeLakeside line270.000434.523270 SH 95 (Sheridan Boulevard) / Harlan StreetSH 95 (Sheridan Blvd.) not signed westbound
county line
LakesideDenver line270.496435.321271A SH 95 (Sheridan Boulevard)Westbound exit and eastbound entrance
City and County of Denver271.549437.016271BLowell Boulevard/Tennyson StreetWestbound exit and eastbound entrance
272.005437.750272 US 287 (Federal Boulevard)
273.015439.375273Pecos Street
274.062441.060274 US 6 west / US 85 south / I-25 (US 87) – Fort Collins, Colorado SpringsThe Mousetrap; western end of concurrency with US 6/US 85; exit 214A on I-25
274.607441.937275AWashington StreetUnnumbered and part of exit 274 eastbound
275.252442.975275B SH 265 north (Brighton Boulevard)
275.545443.447275CYork Street/Josephine StreetEastbound exit and westbound entrance
276.080444.308276A US 6 east / US 85 north (Vasquez Boulevard)Eastbound signage; eastern end of concurrency with US 6/US 85
Steele Street/Vasquez BoulevardWestbound signage

SH 2 (Colorado Boulevard) to US 6 east / US 85 north
US 6 and US 85 appear only on westbound signage
277Dahlia Street/Holly Street/Monaco Street
278.548448.280278 SH 35 (Northfield Quebec Street)
279.086449.145279A I-270 west / US 36 west – Fort Collins, BoulderWestbound exit and eastbound entrance; western end of concurrency with US 36
279.591449.958279BCentral Park Boulevard
280.567451.529280Havana Street
281.560453.127281Peoria StreetUnnumbered and part of Exit 282 westbound
county line
DenverAurora line282.271–
282 I-225 south – Aurora, Colorado SpringsExit 12 on I-225
AdamsAurora283.532456.301283Chambers Road
283.623456.447284 Peña BoulevardDenver International AirportEastbound exit and westbound entrance
284.627458.063285Airport Boulevard
285.727459.833286Tower Road
288.219463.844288 I-70 BL / US 40 west / US 287 north (Colfax Avenue)Left exit westbound; no westbound entrance; I-70 Bus. appears only on westbound signage; western end of concurrency with US 40/US 287
289.028465.145289 E-470 – Fort Collins, Colorado SpringsExit 20 on E-470
292.128470.134292 SH 36 east (Airpark Road)Former US 36 east
295.256475.168295 I-70 BS north – Watkins
299.328481.722299Manila Road
Bennett304.360489.820304 SH 79 north – Bennett
305.259491.267305KiowaEastbound exit only
Arapahoe305.784492.112306SH 36Kiowa, BennettNo eastbound signage; no eastbound entrance; former US 36
315.913508.413316 US 36 east / SH 36 west – ByersEastern end of concurrency with US 36; unsigned SH 36 is former US 36 west
Deer Trail328.329528.394328 I-70 BS south – Deer Trail
340.354547.747340 I-70 BS west – Agate
348.731561.228348Cedar Point
352.340567.036352 SH 86 west – Kiowa
354.537570.572354(no name)

I-70 BL east to US 24 / SH 71 – Limon
Eastbound signage
US 24 – Colorado SpringsWestbound signage
I-70 BL to SH 71 – Limon
SH 71 appears only on eastbound signage
363.025584.232363 US 40 east / US 287 south – Hugo, Kit CarsonEastbound signage; eastern end of concurrency with US 40/US 287

I-70 BL / US 24 west to SH 71 – Limon
Westbound signage; western end of concurrency with US 24
371.482597.842371Genoa, HugoHugo appears only on westbound signage
Kit Carson394.564634.989395Flagler
Seibert405.065651.889405 US 24 east / SH 59 – SeibertEastern end of concurrency with US 24
419.311674.816419 SH 57 – Stratton
Burlington436.788702.942437 I-70 BL / US 385 (Lincoln Street)I-70 Bus. appears only on eastbound signage
438.225705.255438 I-70 BL / US 24 (Rose Avenue)I-70 Bus. appears only on westbound signage; western end of concurrency with US 24
449.589723.543 I-70 / US-24 east – Goodland, SalinaContinuation into Kansas
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

See also[edit]


  1. ^ a b c Colorado Department of Transportation (n.d.). "Segment Descriptions for Highway 070: From RefPoint 0 To RefPoint 500". Colorado Department of Transportation. Archived from the original on May 26, 2012. Retrieved February 16, 2008.
  2. ^ a b c d e f g h i j DeLorme (2002). Colorado Atlas & Gazetteer (Map) (2002 ed.). 1 in:2.5 mi. Yarmouth, ME: DeLorme. ISBN 0-89933-288-9. OCLC 52156345.
  3. ^ Grand Junction Visitor & Convention Bureau. "Grand Junction Colorado: Trip Planning". Grand Junction Visitor & Convention Bureau. Archived from the original on February 6, 2009. Retrieved February 22, 2009.
  4. ^ a b c d e f g h Colorado Department of Transportation. "The History of I-70 in Colorado". Colorado Department of Transportation. Retrieved April 1, 2008.
  5. ^ a b Weingroff, Richard F. (Summer 1996). "Dwight D. Eisenhower System of Interstate and Defense Highways Engineering Marvels". Public Roads. Washington, DC: Federal Highway Administration. 60 (1). Retrieved February 15, 2008.
  6. ^ a b c d Colorado Department of Transportation. "CDOT Fun Facts". Colorado Department of Transportation. Retrieved March 27, 2015.
  7. ^ Flat Iron Construction Company. "Glenwood Canyon Corridor". Flat Iron Construction Company. Retrieved April 20, 2009.
  8. ^ a b c d e f g Stufflebeam Row, Karen; LaDow, Eva; Moler, Steve (March–April 2004). "Glenwood Canyon 12 Years Later". Public Roads. Washington, DC: Federal Highway Administration. 67 (5). Retrieved August 9, 2009.
  9. ^ Federal Highway Administration (October 22, 2008). "Bicycle and Pedestrian Guidance". Federal Highway Administration. Retrieved April 30, 2008.
  10. ^ Paul, Jesse (August 1, 2021). "I-70 in Glenwood Canyon will remain closed after CDOT finds damage 'unlike anything they had seen before'". The Colorado Sun. Archived from the original on August 3, 2021.
  11. ^ Zimmermann, Karl (2004). Burlington's Zephyrs. Saint Paul, Minnesota: MBI Publishing Company. pp. 38–40. ISBN 978-0-7603-1856-0.
  12. ^ Buena Vista Chamber of Commerce (April 29, 2009). "Collegiate Peaks Scenic Byway/Highway of the Fourteeners". Buena Vista Chamber of Commerce. Archived from the original on October 30, 2010. Retrieved June 13, 2009.
  13. ^ a b c d e f g h Weingroff, Richard (December 29, 2008). "Why Does I-70 End in Cove Fort, Utah?". Ask the Rambler. Federal Highway Administration. Retrieved June 7, 2009.
  14. ^ a b c d e f Colorado Department of Transportation. "Eisenhower Tunnel". Colorado Department of Transportation. Retrieved June 15, 2009.
  15. ^ a b Colorado Department of Transportation (December 11, 2014). "Work to Realign I-70 Traffic Through Veterans Memorial Tunnel Scheduled to Begin Saturday Evening" (Press release). Colorado Department of Transportation. Retrieved February 17, 2015.
  16. ^ Colorado Department of Transportation. "Structure List for Highway 070". Colorado Department of Transportation. Archived from the original on May 26, 2012. Retrieved July 1, 2011.
  17. ^ National Park Service (July 19, 2007). "Rocky Mountain National Park: The Dakota Hogback". National Park Service. Retrieved July 21, 2009.
  18. ^ Federal Highway Administration (2009). US 36 Corridor Project, Denver, Colorado Metropolitan Area: Environmental Impact Statement. Federal Highway Administration. p. 402 – via Google Books.
  19. ^ Colorado Department of Transportation. "Straight Line Diagram (for I-70)". Colorado Department of Transportation. Archived from the original on September 8, 2009. Retrieved September 21, 2009.
  20. ^ "A Need for Speed(ways): Colorado's Long and Winding Road Before Joining Eisenhower's Interstate Plan". Rocky Mountain News. June 29, 2006. Archived from the original on July 17, 2011. Retrieved June 13, 2009.
  21. ^ Colorado Tourism Office. "Lets Talk Colorado: Limon". Colorado Tourism Office. Retrieved July 23, 2009.
  22. ^ Colorado Tourism Office. "Lets Talk Colorado: Driving to Colorado from the Kansas State Line: I-70 and Hwy. 50 West". Colorado Tourism Office. Retrieved July 23, 2009.
  23. ^ a b c d e f g h i j k l m n o p q Associated Cultural Resource Experts (2002). Highways to the Sky: A Context and History to Colorado's Highway System. Colorado Department of Transportation. Retrieved May 22, 2009.
  24. ^ Noeth, Louise Ann (2002). Bonneville: The Fastest Place on Earth. St. Paul, MN: MotorBooks/MBI Publishing Company. p. 18. ISBN 0-7603-1372-5. OCLC 50514045. Retrieved August 9, 2009 – via Google Books.
  25. ^ Weingroff, Richard F. (January 1, 2009). "U.S. 6: The Grand Army of the Republic Highway". Highway History. Federal Highway Administration. Retrieved May 24, 2009.
  26. ^ Rand McNally (1946). "Southwest (Colorado, New Mexico)" (Map). Road Atlas. Scale not given. Chicago: Rand McNally. p. 24. Retrieved May 5, 2008 – via Broer Map Library.
  27. ^ a b c Colorado Department of Transportation. "Eisenhower Memorial Bore". Colorado Department of Transportation. Retrieved July 25, 2009.
  28. ^ a b c d Thomas, Ryland; Williamson, Samuel H. (2020). "What Was the U.S. GDP Then?". MeasuringWorth. Retrieved September 22, 2020. United States Gross Domestic Product deflator figures follow the Measuring Worth series.
  29. ^ Colorado Department of Transportation. "Edwin C Johnson Bore". Colorado Department of Transportation. Retrieved July 25, 2009.
  30. ^ Howard, Jane (December 8, 1972). "Janet Fights the Battle of Straight Creek Tunnel". Life. pp. 49–52. Retrieved June 7, 2017 – via Google Boosk.
  31. ^ Colorado Department of Transportation. "Maximum Grades on Colorado Mountain Passes". Colorado Department of Transportation. Retrieved January 8, 2016.
  32. ^ a b Garner, Joe (August 31, 1999). "Freeway Opened the State to the Rest of the U.S." Rocky Mountain News.[permanent dead link]
  33. ^ Scotese, Thomas; Ackerman, John (1992). "Engineering Considerations for the Hanging Lake Tunnel Project, Glenwood Springs, Colorado" (PDF). International Society of Explosives Engineers. Archived from the original (PDF) on February 10, 2005. Retrieved April 30, 2009.
  34. ^ McGregor, Heather (May 22, 1994). "Old Tires to Heal Glenwood Scar: Highway Eyesore Dates to 1930s". The Denver Post. p. C7.
  35. ^ "Travel Advisory; New I-70 Stretch Helps Skiers". The New York Times. November 1, 1992. Retrieved September 8, 2009.
  36. ^ "Nation Briefings". Chicago Sun-Times. October 15, 1992.
  37. ^ Williams, Leroy (June 8, 1993). "Glenwood Canyon Traffic Can Savor Delay-Free Season". Rocky Mountain News.[page needed]
  38. ^ "Costliest Rural Freeway: $100 an Inch". Fresno Bee. November 26, 1972. p. B4. Retrieved February 6, 2021 – via
  39. ^ American Society of Civil Engineers. "Outstanding Civil Engineering Achievement Award". American Society of Civil Engineers. Archived from the original on May 9, 2008. Retrieved February 24, 2008.
  40. ^ Edwards & Kelsey. "I-95/I-276 Interchange Project Meeting Design Management Summary – Draft: Design Advisory Committee Meeting #2" (PDF). Pennsylvania Turnpike Commission. Retrieved August 3, 2009.
  41. ^ Sofield, Tom (September 22, 2018). "Decades in the Making, I-95, Turnpike Connector Opens to Motorists". Levittown Now. Retrieved September 22, 2018.
  42. ^ Weingroff, Richard. "Why Does The Interstate System Include Toll Facilities?". Ask The Rambler. Federal Highway Administration.
  43. ^ Miller, Blair (August 10, 2021). "USDOT approves quick disbursement of $11.6M for Glenwood Canyon repairs as CDOT work continues". KMGH. Archived from the original on August 13, 2021.
  44. ^ "I-70 Glenwood Canyon Safety Closures". Colorado Department of Transportation. August 11, 2021. Retrieved August 14, 2021.
  45. ^ "I-70 through Glenwood Canyon partially reopens; full reopening may not happen until Thanksgiving". Colorado Sun. August 14, 2021. Retrieved August 14, 2021.
  46. ^ Geary, Edward A. "Interstate 70". Utah History to Go. State of Utah. Retrieved February 16, 2008.
  47. ^ a b "Army Rights Tipped Truck Carrying Navy Torpedoes". The Spokesman-Review. Spokane, WA. Associated Press. August 2, 1984. p. 10. Retrieved September 24, 2009 – via Google News.
  48. ^ Getlin, Josh (September 20, 1987). "Record of Risk-Free Transportation Torpedoed by Denver's Experience". Los Angeles Times. p. 26. Retrieved September 24, 2009.
  49. ^ "Errors Many in Torpedo Incident". Eugene Register-Guard. August 10, 1984. p. 14A – via Google News.
  50. ^ Kowalski, Robert (February 26, 1990). "Hazardous Cargo at Heart of Controversy". The Denver Post.[page needed]
  51. ^ Flynn, Kevin (December 16, 2003). "This Mousetrap Wasn't a Snap". The Denver Post.[page needed]
  52. ^ Leasca, Stacy (January 13, 2014). "Colorado Replaces Marker 420 with 419.99 to Foil 'Weed Enthusiasts". Los Angeles Times. Retrieved April 21, 2015.
  53. ^ "Central 70 Project". Colorado Department of Transportation. Retrieved February 8, 2021.
  54. ^ "Project Snapshot" (PDF). Central 70. Colorado Department of Transportation. April 2019. Retrieved February 8, 2021.
  55. ^ Murray, Jon (April 17, 2017). "Activism, Lawsuits Could Delay or Derail the Massive I-70 Expansion in Denver – But Are They Long Shots?". The Denver Post. Retrieved September 26, 2017.
  56. ^ Paul, Jesse (August 24, 2017). "CDOT picks Kiewit Meridiam Partners to lead $1.2 billion I-70 expansion, as project's controversy simmers". The Denver Post. Retrieved September 26, 2017.
  57. ^ a b Colorado Department of Transportation. "Highway Data Explorer, Online Transportation Information System". Colorado Department of Transportation. Archived from the original on September 10, 2012. Retrieved September 8, 2016.
  58. ^ "Highway 006M between 62.305 and 88.895". CDOT Online Transportation Information System. Retrieved March 27, 2021.
  59. ^ Lott, Renelle (October 31, 2012). "Ribbon Cutting Marks Upcoming November Opening of new I-70 West Parachute Interchange" (Press release). Garfield County, Colorado. Archived from the original on May 16, 2013. Retrieved February 27, 2013.
  60. ^ "Highway 006L between 88.895 and 91.24". CDOT Online Transportation Information System. Retrieved March 28, 2021.
  61. ^ Colorado Department of Transportation. "Highway Data Explorer". Online Transportation Information System. Colorado Department of Transportation. Archived from the original on September 10, 2012. Retrieved August 31, 2017.

External links[edit]

Route map:

KML is from Wikidata

Interstate 70
Previous state:
Colorado Next state: