List of gaps in Interstate Highways
|Dwight D. Eisenhower National System of Interstate and Defense Highways|
Interstate Highways in the 48 contiguous states
|Formed:||June 29, 1956|
|Interstates:||Interstate X (I-X)|
There are gaps in the Interstate Highway system, where the roadway carrying an Interstate shield does not conform to the standards set by the Federal Highway Administration (FHWA), the body that sets the regulations for the Interstate Highway System. For the most part, the Interstate Highway System in the United States is a connected system, with most freeways completed; however, some Interstates still have gaps. These gaps can be due to unconnected segments of the same route or from failure of the road to fully conform to Interstate standards by including such things as at-grade crossings, traffic lights, undivided or narrow freeways, or movable bridges (lift bridges and drawbridges). This article deals with present day gaps, as such examples were far more numerous during construction of the Interstate Highway System and the upgrading of existing roads to meet these standards, which did not occur everywhere at the same time. Temporary gaps, such as lane closures that reduce traffic to one lane and reduce speed limits, are also excluded.
True gaps are where two disjoint sections of road have the same Interstate highway number and can reasonably be considered part of "one highway" in theory, based on the directness of connections via other highways, or based on future plans to fill in the gap in the Interstate, or simply based on the shortness of the gap. The two sections are either not physically connected at all, or they are connected but the connection is not signed as part of the highway. It should be noted that most of these gaps (except for the one on I-95) exist because the two segments are actually two unrelated highways that were built at different times, but assigned the same number; many times, the same number was assigned to the second segment with the intention of eventually connecting it to the first segment.
- Interstate 49 currently has two sections: one from Lafayette, Louisiana, to Shreveport, Louisiana, and another section from Kansas City, Missouri, to Pineville, Missouri. This gap is expected to be eventually closed.
- Interstate 69 has six sections: the original alignment runs from Indianapolis, Indiana, to Port Huron, Michigan. On October 2, 2006, a segment of I-69 opened in Tunica and DeSoto counties in Mississippi. Another section exists from near Evansville, Indiana to Scotland, Indiana, and is under construction to Bloomington, Indiana. This section is expected to be connected to the original I-69 in Indianapolis in 2016. In December 2011, a section southwest of Corpus Christi, Texas opened as well. Also in late 2011, the section of the Wendell H. Ford Western Kentucky Parkway between I-24 and Exit 38/ Pennyrile Parkway became signed as I-69. In 2012, a portion of US 59 between Houston and Cleveland, Texas became part of I-69. On February 28, 2013, a portion of US 59 between Houston and Rosenberg, Texas became part of I-69.
- Interstate 73 has two sections: a section of the Greensboro Urban Loop in Greensboro, North Carolina, the only section of I-73 signed with normal Interstate shields, and one concurrent with the entire section of I-74 from Ulah to Ellerbe, North Carolina. On the other segments (where I-73 is cosigned with Interstate 74 and U.S. Route 220) the exact signage varies. However, immediately south of Greensboro, I-73 is signed FUTURE. Further south along the freeway, the Interstate is signed INTERSTATE
- Interstate 74 currently has five sections, one heading west from Cincinnati, Ohio, to Davenport, Iowa; one from the Virginia/North Carolina line along Interstate 77 south/east to a point southeast of Mount Airy, North Carolina; one running concurrent with US 311 around High Point connecting with I-85; one concurrent with the entire section of I-73 from Ulah to Ellerbe, North Carolina; and from west of Laurinburg to south of Lumberton, North Carolina, at Interstate 95. Other sections up to freeway standards are signed with I-74 shields that have FUTURE instead of INTERSTATE. Future I-73 shields are also placed along some of these sections. North Carolina is currently working on connecting all its sections of I-74, though the gap to Cincinnati will remain for the foreseen future.
- The eastern Interstate 86 currently has two sections. One runs for 197 miles (317 km) from I-90 in North East, Pennsylvania, to exit 56 in Elmira, New York. The second section is a 9.9-mile (15.9 km) stretch outside of Binghamton running from I-81 in Kirkwood to exit 79 in Windsor. I-86 will eventually run from North East, Pennsylvania, to the New York State Thruway (I-87) near Harriman, New York. All the designated sections and gaps in New York are part of New York State Route 17.
- Interstate 95. Probably the best-known and most notoriously confusing of all the Interstate gaps, I-95 is discontinuous in Lawrence Township, New Jersey (near Trenton). Coming north from Philadelphia, Pennsylvania, I-95 loops around the north side of Trenton and ends at U.S. Route 1, where it becomes I-295, which heads back south, heading to southern New Jersey. The other section of I-95 begins on the Pennsylvania Turnpike at the Pennsylvania/New Jersey state line, heads east into New Jersey along a spur of the New Jersey Turnpike, then heads north along the New Jersey Turnpike mainline, though it is only signed as far down the NJ Turnpike as I-195. Originally I-95 was planned to have left the alignment north of Trenton and headed northeast to Interstate 287 and run east along I-287 to Exit 10 on the Turnpike, but the Somerset Freeway was never built. Extensions over the years have taken I-95 several miles further north to the US-1 interchange northeast of Trenton, and along the New Jersey Turnpike to the Pennsylvania state line. An interchange is under construction, connecting the southern alignment with the Pennsylvania Turnpike, and I-95 will be rerouted via it, with the part north of that interchange becoming an extension of I-195. (It was originally considered to be an extension of I-295.)
Gaps where different criteria constitute contradictory circumstances.
- The southern end of I-165 ends at Water street in downtown Mobile in Alabama. Traffic going to I-10 has to drive through downtown streets in order to Access I-10 from there. Interestingly, I-165 was originally intended to be I-110, but was re-numbered to avoid a connection gap to I-10.
- I-265. The Indiana portion of I-265 does not yet connect with the Kentucky portion of I-265. Each of the two segments, circling the outskirts and suburbs of Louisville, ends before crossing the Ohio River, making them completely in separate states, thus following numbering guidelines. Plans for constructing a bridge to connect the two segments have been finalized, though the project is far from complete.
- I-90 at the Chicago Skyway — Historically, the Skyway was commonly considered to be, and was signed as, part of I-90 (originally I-94). However, around 1999, the City of Chicago determined it may never have applied for approval to sign it as an Interstate. (It also is not designed to Interstate standards.) The city re-signed the Skyway, and it is now mostly posted with "TO I-90/94" signs with a few older signs remaining. However, the Illinois Department of Transportation has always and continues to report the Skyway as part of the Interstate system, and the Federal Highway Administration still considers it as such. A FHWA legal memo says "There is no doubt about it. The Chicago Skyway is officially part of I-90 that (has) always been included in the Dwight D. Eisenhower National System of Interstate and Defense Highways."
- The northern end of the I-99 freeway ends less than a mile from I-80 in Pennsylvania, and motorists can continue north on US 220/PA 26 along a surface street to grade-level ramps to access I-80, which is planned to overlap in the eastward direction with I-99 northbound, once the extension of I-99 is fully complete.
Freeway gaps occur where the Interstate is signed as a continuous route, but part or all of it is not up to freeway standards. This includes drawbridges where traffic on the Interstate can be stopped for vessels. This does not include facilities such as tollbooths, toll plazas, agricultural inspection stations, or border stations.
At-grade intersections and traffic lights
Several Interstates in rural areas of the U.S. have at-grade intersections (including median breaks) with minor farm access roads. This is usually due to the lack of an old highway; the need to provide access to property that was accessed via the road prior to its upgrade to an Interstate; and the high cost to construct an interchange for the small amount of traffic that would use such a connection or to build a frontage road parallel to the freeway to the nearest interchange.
- I-19 between North West Avenue and its southern terminus at West Crawford Street at North Sonoita Avenue, in Nogales, Arizona consists of surface roads with traffic lights.
- I-35 in the Flint Hills of Kansas along with I-10 and I-40 in remote areas of west Texas have several at-grade access points for cattle ranches. I-40 also has access to dirt roads in western North Carolina.
- Several toll-portions of the Interstate have RIRO-style at-grade intersections albeit restricted to maintenance vehicles seeing that consumers must pay the toll.
- I-70 uses part of US 30 along a surface road in Breezewood, Pennsylvania, to get between the freeway heading south to Hancock, Maryland, and the ramp to the Pennsylvania Turnpike. This is probably the best-known instance of traffic lights on an interstate. There used to be a sign of a policeman pointing at drivers leaving the Pennsylvania Turnpike to enter US 30, saying, "You! Slow Down!" Local businesses have lobbied to keep the gap to avoid loss of business (Map).
- I-676 has a surface street section at the west end of the Ben Franklin Bridge in Philadelphia, Pennsylvania, because of historically significant areas. Signage and the Federal Highway Administration consider I-676 to use the surface streets; the Pennsylvania Department of Transportation and the New Jersey Department of Transportation consider I-676 to be continuous across the Ben Franklin Bridge, even though the bridge, built in 1926, is not up to Interstate standards (Aerial photo). This does not specifically violate Interstate standards, however, as the two separated segments of I-676 are in different states.
- I-78 travels along a one-way pair of surface streets, 12th Street and 14th Street, in Jersey City, New Jersey, between the end of the New Jersey Turnpike Newark Bay Extension and the Holland Tunnel, which leads into New York City. Between the two aforementioned points are four signalized intersections.
- I-180 in Cheyenne, Wyoming, has no parts built to Interstate standard; in fact the interchange with I-80 is just a simple diamond interchange with two traffic lights on I-180, however it is expressway-quality with a few grade-separations (Map).
- I-585 in Spartanburg, South Carolina, is cosigned with US 176, in which I-585 shields are present in beyond the point where it ceases to be a freeway, having passed through traffic lights. There also exists a sign that marks the road there as "I-585 Business Spur" and hence it is unclear whether that surface section of US 176 also belongs to I-585.
- I-690 in Syracuse, New York, has a traffic light 12 days each year for buses to carry Great New York State Fair attendees from parking areas across the road to the fair.
- The northbound lanes of I-5 in Washington state intersect with an at-level pedestrian crosswalk approximately 100 feet south of the Canadian border. This crosswalk allows pedestrians access to a monument which is part of Peace Arch State Park.
Undivided, narrow and curvy freeways
This section addresses two-lane freeways and other narrow or undivided freeway sections of the Interstate, excepting instances of continuing routes using one-lane ramps and merge leads. Narrow gaps between opposing directions with jersey barriers taller than four feet (1.2 m) are excluded from this section.
- I-35E in Minnesota travels along a narrow parkway for about 3.5 miles (5.6 km) from near downtown St. Paul south to Minnesota State Highway 5. Heavy trucks are forbidden from using this stretch, and the speed limit is reduced to just 45 mph (72 km/h).
- I-40 in the first 15 miles (24 km) east into North Carolina in the Harmon Den Wildlife Management Area has several S-curves, a Jersey barrier with extremely narrow left shoulders and a few at-grade intersections albeit in RIRO style.
- I-64 has an S-curve near Waynesboro, Virginia, with its sinewave-like curvature at approximately two-mile (3.2 km) wavelength and three-quarters-mile (1.2 km) amplitude, which puts this stretch at a substandard level of safety for Interstate Highways.
- I-70 is one-lane-only for through traffic for several thousand feet in Wheeling, West Virginia, where the highway enters the Wheeling Tunnel and crosses the Ohio River on the Fort Henry Bridge. Nearby I-470 provides relief from this situation.
- The Murray Baker Bridge, which carries I-74 over the Illinois River in Peoria, Illinois, has no shoulders, which makes it too narrow for Interstate standards. Trucks of all sizes, however, are permitted on this bridge.
- The Mackinac Bridge, which carries I-75 over the Straits of Mackinac between St. Ignace and Mackinaw City, Michigan, has no wide median or hard shoulders due to space constraints, nor does it have a jersey barrier; instead, it has a 4-inch-tall (10 cm) divider between the opposing directions of the green grate lanes, and the north side of the bridge approaching the toll booth uses a double-yellow line to separate opposing sides. The speed limit is also reduced to 45 mph (72 km/h) for cars and 20 mph (32 km/h) for trucks on the bridge. The highway returns to Interstate standard until it reaches the Sault Ste. Marie International Bridge, which carries only two undivided lanes of the Interstate to its terminus at the Canadian border.
- I-476 in Clarks Summit, Pennsylvania (north of Scranton), near its terminus with I-81 has only one lane northbound on its approach to the toll booths, and is a divided two-lane freeway (in the same manner as I-93 below) from the toll booths to its terminus with US 6 and between the double trumpet interchange with I-81. The hilly terrain and narrow right-of-way, combined with a tight 180-degree curve contributed to keeping a full four-lane freeway from being constructed.
- The Thousand Islands Bridge, which carries I-81 over part of the Saint Lawrence River, is an undivided road with one lane in each direction.
- The bridge that carries I-81 over the Potomac River has no shoulders, which makes it too narrow for Interstate standards. Trucks of all sizes, however, are permitted on this bridge. 
- I-93 is a two-lane divided parkway, or a "super-two", through Franconia Notch in New Hampshire. A four-lane Interstate Highway was once proposed here, but the concept was abandoned because of environmental concerns, in part because of vibrations that could harm the Old Man of the Mountain rock formation (prior to the formation's 2003 collapse). This section of highway was for many years marked as US 3 and "To I-93", but these have now been replaced with regular I-93 signs. The Federal Highway Act of 1973 exempts this stretch from the Interstate Highway standards that apply elsewhere, and this highway is considered to be I-93 for all practical purposes.
- I-95 has substandard overpass clearances for 10 miles (16 km) near Benson, North Carolina, and has warning signs for this condition.
- Some stretches of Interstate highway use a barrier transfer machine on some bridges where it would be too costly to upgrade/rebuild to a higher-capacity bridge. In any case the traffic distribution is strongly asymmetric depending on the hour of the day. This kind of bridge typically contains undivided lanes without the flexible Jersey barrier that is manipulated by machines.
By Interstate standard, all bridges on the Interstate system must be fixed as to not interrupt the flow of traffic. Several bridges on the system, however, are movable:
- Interstate 5 crosses the Columbia River from Portland, Oregon, to Vancouver, Washington, on the Interstate Bridge, a vertical-lift bridge. There are plans in existence to replace this bridge with a high-level bridge over the river.
- Interstate 110 has a drawbridge across the Back Bay of Biloxi in Biloxi, Mississippi.
- Interstate 64—the Hampton Roads Beltway—crosses the South Branch of the Elizabeth River in Chesapeake, Virginia, on the High Rise Bridge, which is a drawbridge. This is a segment of I-64 that happens to not have any East and West signs posted on it, because of the highway's bending to a configuration that is opposite from its original compass direction.
- Interstate 264 has a drawbridge, the Berkley Bridge, crossing the Elizabeth River in Norfolk, Virginia.
- Interstate 278 has a drawbridge across the Bronx River in New York City.
- Interstate 280 (New Jersey) has a drawbridge, the Stickel Memorial Bridge, crossing over the Passaic River between Newark and Harrison, New Jersey.
- Interstate 95 and Interstate 495 pass together as the Capital Beltway over the Potomac River on the Woodrow Wilson Bridge, a double-leaf bascule span. Even though the original bridge was replaced in the 2000s, the new bridge also has a draw span, albeit with more vertical clearance resulting in fewer openings than the old bridge — about 65 per year, an average of about one every six days.
- Interstate 695 has a drawbridge over Curtis Creek, south of Baltimore and just west of the Francis Scott Key Bridge. However, this section of the Baltimore Beltway is not part of the Interstate Highway System, and is officially Maryland Route 695 despite the Interstate signage on the highway.
Other movable bridges on the Interstate System have been replaced after spending many years as part of the system. These include:
- Interstate 75 had a bascule bridge from 1960 to 1988 at Zilwaukee, just north of Saginaw; the high-level Zilwaukee Bridge replaced it on December 23, 1987, for northbound traffic, and on September 19, 1988, for southbound traffic. Interstate 675 was built as an in-town bypass of the bascule bridge prior to the construction of the tall Zilwaukee bridge. Since the completion of the tall Zilwaukee bridge in 1987, I-675 has had less traffic than its capacity; though it is a feasible detour for bridge, or other maintenance between both ends of the loop.
- Interstate 280 formerly had a drawbridge, the Craig Bridge, in Toledo, Ohio. The fixed-span Veterans' Glass City Skyway replaced the drawbridge on the Interstate Highway in 2007.
Auxiliary Interstates (also known as three-digit Interstates) are intended to connect to their parent either directly or via a same-parented Interstate (like I-280 in California being connected to I-80 via I-680). Often, these connection gaps occur to eliminate concurrencies between other three-digit routes. Freeway gaps (signed or unsigned) that officially connect auxiliary routes to the parent are excluded.
- Officials planned Interstate 110 to be constructed in Mobile, Alabama, however local opposition curtailed construction through Mobile which prevented a solid connection to I-10, and was re-numbered as Interstate 165 instead as it at least connected to I-65.
- Interstate 210 in California does not connect directly to Interstate 10, although I-210 is continuous with California State Route 210, which does connect to I-10, and California is petitioning to have that portion signed as Interstate 210 also. When that happens, this gap will disappear. I-210 does not connect to any of the spurs of I-10, with the exception of a short, unsigned, unfinished section of Interstate 710 which connects to Interstate 110 and State Route 110 only via surface streets.
- None of the spurs of I-78 (I-278, I-478, I-678, I-878) connect to its parent. I-78 was planned to extend through New York City and end as two branches, where I-295 and I-695 now end at I-95. I-478 comes the closest, and would have intersected if the Westway project were not canceled; I-278, the only I-78 spur to leave New York City, was planned to extend northwest to I-78 at Route 24. Since all the spurs are interconnected, only one of them needs to be eventually connected to its parent route for all of them to conform to standards.
- I-585 used to connect with I-85 in Spartanburg, South Carolina, but I-85 was moved to a new bypassing route, and now I-585 ends at the I-85 Business loop. The signed connection to I-85 is via a surface section of US 176.
Instances of triple-digit designations that cross state lines when they connect to the Interstate in the neighboring state but do not reconnect in that state are excluded from this list. But there are even instances of triple-digit interstates that cross state borders into states where their parent does not even exist. However, Interstate 238 in the San Francisco area is an example of a triple-digit Interstate whose parent doesn't exist at all, on a side note: Every I-x80 designation in the San Francisco area was taken at the time I-238 was commissioned, in which an instance of a California state route with an x80 designation eliminated a candidate for a 3-digit Interstate designation, as California law prohibits state highways from having common numbers with co-existing US and Interstate highways; fortunately, the national policy of the geographical basis for numbering of US and Interstate highways being inverse of one another facilitated compliance to California's state policy.
Examples of these connection gaps are subject to dispute with unofficial, unsigned concurrencies with other routes to the parent.
- In five cases—Interstate 66, I-76, I-84, I-86, I-88 —the same primary interstate route number is used on two separate, unconnected lengths of roadway, one in the eastern portion of the country and one in the western portion. These gaps are intentional — the two segments of roadway are not planned to be linked together, nor is there any official or causal concurrency to rectify their discontinuity, seeing there is no signed or documented concurrency on other east-west routes whatsoever.
- Weingroff, Richard F. (Summer 1996). "Federal-Aid Highway Act of 1956, Creating the Interstate System". Public Roads (Washington, DC: Federal Highway Administration) 60 (1). Retrieved March 16, 2012.
- "Report to SCOH May 19, 2012".
- "Alliance for I-69 Texas - More Houston Areas Freeway Added to Interstate 69".
- Malme, Bob. "I-73 Segment 4". Self-published. Retrieved November 19, 2009.[unreliable source]
- Malme, Bob. "I-73 Segment 9/I-74 Segment 10". Self-published. Retrieved November 19, 2009.[unreliable source]
- Malme, Bob. "I-74 North Carolina Progress Page". Self-published. Retrieved August 28, 2009.[unreliable source]
- Rose, Joel (August 21, 2010). "At Last, I-95's Missing Link Hits The Road". National Public Radio.
- "Home". Ohio River Bridges Project of Kentucky and Indiana. Kentucky Transportation Cabinet and Indiana Department of Transportation. Retrieved August 28, 2009.
- Office of Operations. "Tolling and Pricing Program". Federal Highway Administration. Retrieved August 28, 2009.
- Samuel, Peter (June 29, 2005). "Skyway Is Interstate 90 Unless State Withdraws Reports: Feds". TollRoadsNews. Archived from the original on September 22, 2008.
- Roig-Franzia, Manuel (November 22, 2001). "The Town That Stops Traffic: Travelers Encounter Way Station as Way of Life in Breezewood". Washington Post. p. B1.
- Google Inc. Google Maps – Intersection of 14th St (ostensibly 78 West) and Erie St (Map). Cartography by Google, Inc. http://maps.google.com/maps?q=Jersey+City+NJ&t=h&ie=UTF8&ll=40.731861,-74.042729&spn=0.001785,0.004828&z=18&layer=c&cbll=40.731839,-74.042516&panoid=5dvrrt9-DUeW4FQkik1ltg&cbp=12,273.3558391375674,,0,3.999999999999998. Retrieved August 28, 2009.
- "I-81 Crossing of the Potomac River". AARoads. Self-published. Retrieved July 1, 2012.
- Weingroff, Richard (April 7, 2011). "Interstate System Conditions and Performance". Highway History. Federal Highway Administration. Retrieved August 20, 2012.
- Project staff. "Home". Columbia River Crossing. Oregon Department of Transportation and Washington State Department of Transportation. Retrieved August 28, 2009.
- Highway Information Services Division (2007). Highway Location Reference. Maryland State Highway Administration. Retrieved April 15, 2009.
- Ann Arundel County (PDF)
- Highway Services Division (2010). "Movable Bridges on State Maintained Highways" (PDF). Maryland State Highway Administration. Retrieved October 18, 2010.
- Staff writer (September 19, 1988). "Zilwaukee Bridge Now Open North, South—Partly". Toledo Blade. p. 1.