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Interstate 270 (Colorado)

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Interstate 270 marker

Interstate 270
I-270 highlighted in red
Route information
Maintained by CDOT
Length 7.107 mi[2] (11.438 km)
Existed 1965[1] – present
Major junctions
West end I-25 / US 36 in Welby
  I-76 in North Washington
US 6 / US 85 / SH 2 at Commerce City
East end I-70 / US 36 at Denver
Highway system
Colorado State Highways
SH 266US 285

Interstate 270 (I-270) is a 7-mile-long (11 km) highway in the northeastern part of the Denver–Aurora Metropolitan Area in the U.S. state of Colorado. It overlaps U.S. Highway 36 (US 36) for its entire length. The western terminus of I-270 is at the interchange with I-25 and US 36. It heads eastward to an interchange with I-76, where the mileposts reset because of a previous freeway extension. The freeway heads southeast and comes to meet Vasquez Boulevard, where it enters Commerce City. The road crosses Quebec Street before ending at I-70.

Ground was broken on the first segment of I-270 in 1965, and the freeway was completed three years later, stretching from I-70 to Vasquez Boulevard. The road was then extended to I-76 two years later. The section between I-25 and I-76 was completed in 1999. Since completion, this section has undergone much construction to renew bridges over Clear Creek and Washington Street. Because the western end of I-270 is close to the junction of I-25 and I-76, some traffic movements to I-25 can only be made by using I-76.

Route description[edit]

I-270 begins at an interchange with I-25 in Welby, and is concurrent with US 36. The speed limit through the first section is 45 mph (72 km/h).[3][4] The freeway heads southeastward for about one mile (1.6 km), crossing over Washington Street and State Highway 224 (SH 224), but access is not provided to either road. Mileposts along I-270 reset to zero at the I-76 interchange because it was the original western end of the Interstate.[2][5] Since the I-76 interchange is close to both I-270's western end and to the I-25 / I-76 interchanges, some movements in the interchange are missing. Eastbound I-270 traffic cannot access westbound I-76, nor can eastbound I-76 traffic access westbound I-270. However, traffic on I-25 can access both westbound I-76 and eastbound I-270, thus completing the missing movements. The three interchanges work together by eliminating bottlenecks caused by redundant interchanges.[6]

A sign in a snowy area indicating an exit for I-270 to Fort Collins and SH 35 as the next exit
I-270 exit along I-70

Beyond the I-76 interchange, the speed limit increases to 55 mph (89 km/h).[7] The freeway heads southeast and comes to a westbound exit and eastbound entrance with York Street, and crosses the South Platte River [8] into a commercial area in Adams County. I-270 enters the city of Commerce City,[9] running roughly parallel with the nearby Sand Creek[10] and crossing over SH 265 without an exit.[11][12] Continuing through the city, the route comes to a cloverleaf interchange with Vasquez Boulevard, which carries US 85, SH 2, and US 6.[13] The freeway heads eastward into Denver,[14] where it has an exit at SH 35, a short highway which continues northward along Quebec Street for one mile (1.6 km).[15] Quebec Street provides access for traffic heading to westbound I-70. The route ends shortly thereafter when it merges into I-70.[6]

An aerial photograph
Former site of Stapleton International Airport, located east of I-270. I-270's interchange with I-70 can be seen in the far left

The freeway is maintained by the Colorado Department of Transportation (CDOT), who is responsible for maintaining and constructing transportation infrastructure in Colorado, including highways.[16] As part of this role, CDOT periodically conducts surveys on their highways to measure traffic volume. This is expressed in terms of average annual daily traffic (AADT), which is a measure of traffic volume for any average day of the year. In 2009, CDOT calculated that as few as 56,500 vehicles used I-270 daily east of its western terminus at I-25, and as many as 89,600 vehicles used I-270 daily southeast of York Street in Commerce City.[17] As part of the Interstate Highway System,[18] the entire route is listed on the National Highway System, a system of roads that are important to the nation's economy, defense, and mobility.[19]


1955 map showing planned Interstate highways around Denver

I-270 was constructed in several phases, beginning with a section from I-70 to Vasquez Boulevard. Following this section was another part of the freeway from Vasquez Boulevard west to I-76, and finally a section from US 36 to I-76. This last segment has undergone much more construction, including new bridges and ramps at interchanges.[1]


Construction on I-270 began in 1965. The first portion cost about $2.7 million.[1] It opened in 1968, connecting I-70 to Vasquez Boulevard. Two years later, another two-mile (3.2 km) segment connected the portion already in service to I-80S.[1] I-80S became I-76 in 1976.[20] Construction began on the section between I-76 and I-25 in April 1993 and was finished in September 1999, costing $11.4 million.[1] The mileposts were already established when construction took place, so the route was not assigned new mileposts.[2] Completion of this portion largely decreased traffic problems in the area.[21][22]


The bridges along westbound I-270 over Washington Street were replaced and finished in the late 1990s, costing $12 million.[1] By the end of 1998, the bridges over Clear Creek near the I-76 interchange were completed. In February 2000, a connection between westbound I-270 and westbound US 36 was completed,[23] as was access between I-76 westbound and I-270 westbound.[1][24] The eastbound section between US 36 and I-76, including new bridges over Washington Street and Clear Creek, was completed in March 2002 and totaled $8.5 million.[1][25] Three years later, a flyover ramp was constructed connecting I-25 southbound to I-270 eastbound.[1][26] However, access between I-270 eastbound and I-76 westbound still does not exist.[27][28]


CDOT aims to widen the freeway from four up to six lanes between I-76 and I-70 by 2025.[29][30]

Exit list[edit]

AdamsWelby0.0000.0000 US 36 west (Denver–Boulder Turnpike) – Boulder
I-25 north – Fort Collins
US 36 is the continuation beyond I-25; no exit to southbound I-25 and no entrance from northbound I-25; western terminus; I-25 exit 217
1 I-76 to I-25 south – Grand Junction, Fort Morgan, DenverNo eastbound exit from I-270 to westbound I-76; no eastbound entrance to I-270 from westbound I-76; mileposts reset at this interchange, which was the original start of the freeway; I-76 exits 6A-B
0.3850.620York StreetWestbound exit and eastbound entrance
Commerce City2.3583.7952 US 6 / US 85 / SH 2 (Vasquez Boulevard)Signed as exits 2A (north) and 2B (south)
City and County of Denver4.5697.3534 SH 35 to I-70 west – Denver
5.3788.6555Central Park BoulevardEastbound exit only; westbound exit via I-70
5.9869.634 I-70 east / US 36 – Limon, Kansas CityEastern terminus; I-70 exit 279A
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

See also[edit]


  1. ^ a b c d e f g h i "Interstate 270". 50th Anniversary of the National System of Interstate and Defense Highways. Colorado Department of Transportation. Retrieved January 23, 2011. 
  2. ^ a b c d "Segment Descriptions for I-270". Colorado Department of Transportation. Retrieved December 14, 2011. 
  3. ^ Map of Adams County, Colorado (PDF) (Map). Colorado Department of Transportation. Retrieved January 23, 2011. 
  4. ^ Colorado Department of Transportation. "Route 270B Straight Line Diagram" (PDF). Retrieved January 31, 2011. 
  5. ^ "Mile Marker List for I-270". Colorado Department of Transportation. Retrieved February 1, 2011. 
  6. ^ a b Microsoft; Nokia (January 23, 2011). "I-270" (Map). Bing Maps. Microsoft. Retrieved January 23, 2011. 
  7. ^ Colorado Department of Transportation. "Route 270A Straight Line Diagram" (PDF). Retrieved January 31, 2011. 
  8. ^ "South Platte Cleanup". The Denver Post. May 10, 1997. 
  9. ^ Colorado Highways Map (PDF) (Map). Colorado Department of Transportation. Retrieved February 2, 2011. 
  10. ^ "Sand Creek Cleanup Shows Heart". The Denver Post. September 13, 2004. 
  11. ^ Map of Commerce City, Colorado (PDF) (Map). Colorado Department of Transportation. Retrieved January 23, 2011. 
  12. ^ Colorado Department of Transportation. "Classification List for I-270". Retrieved February 2, 2011. 
  13. ^ "Interchange Information for I-270". Colorado Department of Transportation. Retrieved January 23, 2011. 
  14. ^ Colorado Department of Transportation. "Region List for I-270". Retrieved January 31, 2011. 
  15. ^ Map of Denver, Colorado (PDF) (Map). Colorado Department of Transportation. Retrieved January 23, 2011. 
  16. ^ Colorado Department of Transportation. "About CDOT". Retrieved February 18, 2011. 
  17. ^ Colorado Department of Transportation. "Traffic Information for Highway 270". Retrieved February 18, 2011. 
  18. ^ "Table 3: Interstate Routes in Each of the 50 States, District of Columbia, and Puerto Rico". FHWA Route Log and Finder List. Federal Highway Administration. October 31, 2002. Retrieved February 18, 2011. 
  19. ^ National Highway System: Denver-Aurora, Colorado (PDF) (Map). Federal Highway Administration. March 2005. Retrieved February 18, 2011. 
  20. ^ "Interstate 76". 50th Anniversary of the National System of Interstate and Defense Highways. Colorado Department of Transportation. Retrieved January 23, 2011. 
  21. ^ "I-270 Link to US 36 Hailed as 1.1 Headache-Free Miles". Rocky Mountain News. Denver. August 16, 2003. 
  22. ^ Flynn, Kevin (May 10, 2005). "Denver Gridlock Ranked 9th". Rocky Mountain News. Denver. Retrieved January 24, 2011. 
  23. ^ Auge, Karen (February 22, 2000). "Extension Eases I-270 Passage to US 36". The Denver Post. 
  24. ^ Colorado Department of Transportation. "2008 Annual Report" (PDF). Retrieved February 2, 2011. 
  25. ^ "Metro area CDOT road projects". Rocky Mountain News. October 11, 2006. Retrieved February 7, 2011. 
  26. ^ Leib, Jeffrey (November 23, 2005). "Motorists can Fly from I-25 to I-270". The Denver Post. 
  27. ^ Colorado Department of Transportation. "CDOT Transportation Fact Book 2006" (PDF). Retrieved February 2, 2011. 
  28. ^ Colorado Department of Transportation. "Structure List for I-270". Retrieved February 2, 2011. 
  29. ^ Colorado Department of Transportation. "2025 Interim Regional Transportation Plan" (PDF). Retrieved January 31, 2011. 
  30. ^ Leib, Jeffrey (December 18, 2008). "Construction Projects to Hit Metro-Area Roads". The Denver Post. Retrieved February 1, 2011. 

External links[edit]

Route map: Google

KML is from Wikidata