List of auxiliary Interstate Highways
|Dwight D. Eisenhower National System of Interstate and Defense Highways|
Highway shield for Interstate 295
Interstate Highways in the 48 contiguous states
|Formed:||June 29, 1956|
|Interstates:||Interstate X (I-X)|
The auxiliary Interstate Highways (also called three-digit Interstate Highways) are a supplemental subset of the freeways of the Interstate Highway System of the United States. Similar to the mainline Interstate Highways, these highways also meet all Interstate Highway Standards, they receive the same percentage of federal funding (90%), and they comply with other federal standards. These shorter auxiliary routes branch off of main routes and are numbered based on the number of the parent route, such that all I-x95 routes are supplemental routes for I-95. Auxiliary routes are generally classified as spur routes (which connect to the parent route at one end), bypasses (which connect to the parent route at both ends), or beltways, which form a complete circle intersecting the parent route at two locations. There are some routes which connect to the parent route at one end, but connect to another route at the other end; some states treat these as spurs while others treat these as bypasses. While some exceptions do exist, generally spur routes are numbered with an odd hundreds digit (such as I-395), while bypasses and beltways are numbered with an even hundreds digit (such as I-695). Because longer interstates may have many such supplemental routes, the numbers may repeat in each state along their route, but they will not repeat within a state.
Terminology and guidelines
The first digit of the three digits usually determines whether a route is a bypass, spur, or beltway. The last two digits are derived from the main Interstate Highway. For instance, I-515 contains an odd number in the first digit– "5", and indicates that this freeway is a spur. The last two digits signify the highway's origin. In this case, the "15" in I-515 shows that it is a supplement to I-15.
- It may serve another section of a city or metropolitan area not served by the main freeway (most often the central business district), terminating at a regular city street/avenue or at a substandard freeway, such as I-180 in Lincoln, Nebraska.
- It may represent the first portion of a contemplated extended freeway, one that downgrades to below Interstate standards with plans to upgrade it later on. An example is I-540 in Arkansas.
- It may connect two unrelated Interstate highways—such as I-390 in New York State and I-355 in Illinois do.
- Note that states differ on their interpretation of the numbering convention in this case. In the I-390 example above, the route has both ends at Interstates, but not at the same Interstate on both ends, and is assigned an odd first digit. Another example is I-275 in Tennessee: it is a connector between I-40 and I-75 (a similar case of having both ends at Interstates but not at the same Interstate) and is assigned an even first digit.
Examples of Interstate Highway spur routes are listed below.
- I-110 in California links I-10 with the Port of Los Angeles. This freeway was built before Interstate Highways as the Harbor Freeway. Later, it was adopted into the Interstate Highway System.
- I-180 in North-Central Pennsylvania connects Williamsport and Lycoming County with I-80 in Milton, which does not actually enter Lycoming County. I-180 also serves as a connection to those traveling to New York and I-86 via U.S. Route 15 and the Future I-99 Corridor at its western terminus.
- I-190 in New York connects the cities of Niagara Falls and Buffalo with I-90.
Sometimes, a three-digit Interstate Highway branches off from another three-digit Interstate Highway. These spurs do not connect directly with their parent highways, but are associated with them via the three-digit highways they do intersect with.
Examples are listed below.
- I-380 in Northern California is located at the San Francisco Bay Area. This highway begins at I-280, and it connects with US 101.
- I-190 branches off from I-290 in Massachusetts, and it never connects with its parent, I-90.
- I-795 in Baltimore County, Maryland branches off from I-695.
A bypass route may traverse around a city, or may run through it with the mainline bypassing. In a typical 3-digit Interstate Highway, bypasses usually have both its two termini junctioned with another Interstate highway. Bypass routes are preceded by an even number in the first digit.
Examples of bypass routes are listed below.
- I-215 in Utah travels part of the perimeter of Salt Lake City.
- I-220 in Louisiana serves as a bypass of downtown Shreveport.
- I-440 forms a loop around the south side of Nashville.
In the case of an auxiliary Interstate highway which has both ends at Interstates but not the same Interstate, some states treat these as bypasses while others treat these as spurs — see Spur route above.
A beltway (also known as a loop route) completely surrounds a metropolitan city, and it is often connected with multiple junctions to other routes. Unlike other auxiliary Interstate Highways, beltways do not have termini, however they have a place where the highway mileage resets to zero. Beltways are also preceded by an even number in the first digit.
Some examples of beltways are listed include:
- I-275 in Ohio, Kentucky and Indiana travels around the city of Cincinnati.
- I-465 in Indiana, also called the "USS Indianapolis Memorial Highway" and oftentimes just "465," travels around the city of Indianapolis.
- I-495 in Maryland and Virginia travels around the city of Washington, D.C. and is referred to as "The Capital Beltway".
- The Augusta area in Georgia also has a recent exception. I-520 had conformed to numbering conventions until late 2009 as well, when I-520 was extended in South Carolina back to I-20 and is now a loop.
- In California, an auxiliary route of I-80, numbered I-238 connects San Leandro with Castro Valley, even though there is no I-38 anywhere. The highway was so numbered for simple convenience since it had been previously numbered as State Route 238. After this highway was upgraded to Interstate Highway standards, it was adopted into the Interstate Highway System. A number "I-x80" would have fit it as an auxiliary route of I-80, but at the time of I-238's designation, all of the auxiliary routes numbers of I-80 had already been used in California (Interstates 280 through 980). "I-180" was unavailable because the California Department of Transportation does not allow duplicate route numbers and there was already State Route 180 in existence at the time, though if there was a duplicate state route number as a continuation it would be a valid exception. I-480 is available today but was being used for the Embarcadero Freeway, which has since been demolished. Although I-5 is the next nearest primary Interstate, an I-x05 designation would not conform to the numbering convention because the route only links two auxiliary routes of I-80 (I-580 and I-880).
- In the Los Angeles area, I-210 does not connect with I-10 directly, nor with any other auxiliary Interstate of I-10, although they are connected through numerous other Interstates. I-210 was formerly connected to I-10 by way of a segment of the Orange Freeway that is now designated State Route 57. When State Route 210 is re-signed I-210, it will finally reconnect with I-10.
- New York City has numerous auxiliary routes designated as being from I-78, but none of the auxiliary routes of I-78 actually intersects with it. This is because I-78 was long ago intended to continue farther east from its present terminus at the eastern end of the Holland Tunnel. It was to cross southern Manhattan, then go through the boroughs of Brooklyn and Queens, and from there across Long Island. This entire planned part of I-78 was canceled during the 1970s, after I-278, I-478, I-678, and I-878 were already completely or partially in existence.
- Also in the New York City area, I-495 does not connect with I-95 directly, but it does intersect with I-295, which in turn, intersects with I-95. The connector from the New Jersey Turnpike (which is signed as I-95 in northern New Jersey) to the Lincoln Tunnel was to have been part of I-495 despite not being up to the standards of the Interstate Highway System. The Mid-Manhattan Expressway was to have connected the Lincoln Tunnel with the Queens-Midtown Tunnel, but was canceled due to concerns regarding building such a highway in the densely built Midtown area. The LIE was eventually built from the end of the Queens-Midtown Tunnel to a terminus near Riverhead on Long Island. An extension from there, to cross the end of Long Island Sound to I-95 in Connecticut, was never built, which left I-495 as a spur. The New Jersey approach became New Jersey State Route 495.
- In North Carolina, I-495 does not meet up with I-95. Instead, it connects two auxiliary routes of I-40: I-440 and I-540. When US 64 is upgraded, I-495 will connect with I-95. The route between I-540 and I-95 is currently signed "Future 495" with interstate shields and the word "FUTURE" in place of the cardinal directions.
- In Virginia, I-264 conformed to interstate numbering conventions until 1999, when VA Route 44 east of the I-264/I-64 interchange was renumbered to I-264.
- Pittsburgh, Pennsylvania has two recently created exceptions. I-279 (and I-376, by some interpretations) had conformed to numbering conventions until 2009 when I-376 was extended from its previous terminus in Downtown Pittsburgh to its present terminus north of I-80. I-376 acted as a spur from its parent (I-76) in Monroeville (Allegheny County), but now links with I-76 in Lawrence County. Likewise, I-279 was a loop that met up with its parent (I-79) at two locations in Allegheny County, but now terminates in Downtown Pittsburgh (having been truncated at its intersection with I-376), and functions as a spur route from I-79.
- Sometimes, when a spur route from a mainline Interstate highway does not meet Interstate Highway standards, a state route shield sometimes uses the parent Interstate route number as a suffix to imply that this number was derived from the Interstate Highway's, there are even examples of state route numbers that serve as a physical continuation to circumvent Interstate standards, though business spurs also serve that purpose as well. One example of this would be Virginia State Route 895, which directly connects to I-95 south of Richmond. The road was originally planned as I-895, but did not qualify for federal funding due to its status as a toll road, thus its current status as a state highway.
Short mainline routes
Some mainline routes (one or two-digit Interstates) are sometimes less than half the length of the longest auxiliary Interstates, thus they fall closer to the geographical criteria for auxiliary routes than they do for mainline routes.
- I-27 goes from Lubbock, Texas, to Amarillo, Texas, for 100 miles (160 km).
- I-86 in Idaho is a 63-mile (101 km) connector from I-84 to I-15.
- I-97 runs for 17.6 miles (28.3 km) between Baltimore and Annapolis, Maryland, and does not connect to any other mainline route. It serves as a southward spur from I-895.
Interstate 35E and 35W
There are two short splits of I-35 in Minnesota and Texas. For 42 miles (68 km), I-35W serves the city of Minneapolis, and I-35E serves the city of St. Paul. In the Dallas-Fort Worth Metroplex in Texas, a separate I-35E serves Dallas and I-35W passes through Fort Worth. The Texas highways are longer at 97 and 85 miles (156 and 137 km), respectively.
|Number||Length (mi)||Length (km)||Southern or western terminus||Northern or eastern terminus
|H-201||4.10||6.60||H-1 in Halawa||H-1 in Honolulu||1989||current||Signed as Route 78 until 2004|
|I‑105||17.32||27.87||SR 1 in El Segundo||I-605 in Norwalk||1963||current|
|I‑205||12.97||20.87||I-580 near Tracy||I-5 near Tracy||1970||current|
|I‑305||8.44||13.58||I-80 in West Sacramento||I-80 Bus/US 50/SR 99 in Sacramento||1981||current||Unsigned|
|I‑405||72.15||116.11||I-5 in Irvine||I-5 in Mission Hills||1964||current|
|I‑505||32.98||53.08||I-80 in Vacaville||I-5 in Dunnigan||1977||current|
|I‑605||27.40||44.10||I-405 in Seal Beach||I-210 in Irwindale||1964||current|
|I‑805||28.02||45.09||I-5 in San Ysidro||I-5 in San Diego near the University of California, San Diego||1959||current|
|I‑905||8.96||14.42||I-5 in San Ysidro||Fed. 2 at the United States-Mexico border in Otay Mesa||proposed||—||Proposed auxiliary route to connect to the Mexican border in the San Diego area|
|I-105||3.49||5.62||OR 99 in Eugene||I-5 in Springfield||2011||current|
|I-405||3.53||5.68||I-5 in Portland||I-5 in Portland||1950||current|
|I‑205||36.64||58.97||I-5 in Tualatin, OR||I-5 in Salmon Creek, WA||1975||current|
|I‑405||30.30||48.76||I-5/SR 518 in Tukwila||I-5/SR 525 in Lynnwood||1964||current|
|I‑605||—||—||—||—||proposed||—||Proposed to bypass Seattle|
|I‑705||1.50||2.41||I-5/SR 7 in Tacoma||—||1990||current||Schuster Parkway in Tacoma|
|I‑110||20.43||32.88||SR 47 in San Pedro, Los Angeles||I-10/SR 110 in Los Angeles||1978||current|
|I‑210||48.52||78.09||I-5 in Sylmar||SR 57/SR 210 in Glendora||1964||current|
|I‑710||19.66||31.64||Terminal Island in Long Beach||Valley Boulevard in Alhambra||1983||current|
|I‑110||6.94||11.17||US 98 Bus near Pensacola||I-10 near Pensacola||1969||current|
|I‑110||8.89||14.31||I-10 in Baton Rouge||US 61 in Baton Rouge||1965||current|
|I‑210||12.40||19.96||I-10 near Sulphur||I-10 in Lake Charles||1962||current|
|I‑310||11.25||18.11||US 90 in Boutte||I-10 near Kenner||1993||current|
|I‑510||5.10||8.21||LA 47 in New Orleans||I-10 in New Orleans||1992||current|
|I‑610||4.52||7.27||I-10 at the Orleans-Jefferson Parish||I-10 in New Orleans||1956||current|
|I‑910||9.70||15.61||US 90 Bus in Marrero||I-10 in New Orleans||1999||current||Unsigned|
|I-110||4.10||6.60||US 90 in Biloxi||I-10 in D'Iberville||1988||current|
|I-310||6||10||US 90 near the Port of Gulfport||I-10 in Gulfport||proposed||—||Future spur into Gulfport, MS|
|I-110||0.92||1.48||Av Abraham Lincoln at the United States-Mexico border in El Paso||I-10 in El Paso||1967||current||Shortest signed Interstate in the country|
|I-410||49.49||79.65||Beltway around San Antonio||1959||current|
|I-610||37.97||61.11||Beltway around Houston||1975||current|
|I‑215||54.50||87.71||I-15 in Murrieta||I-15 in Devore||1982||current|
|I‑115||1.19||1.92||I-15/I-90 in Butte||Iron Street in Butte||1971||current|
|I‑315||0.83||1.34||I-15 in Great Falls||I-15 Bus/US 89 in Great Falls||1960||current||Unsigned|
|I‑215||13.00||20.92||I-15/Clark County Route 215 near Paradise||I-515/US 93/SR 564 in Henderson||1996||current|
|I‑515||20.54||33.06||US 93/US 95 in Henderson||I-15/US 93/US 95 in Las Vegas||1976||current|
|I‑215||29.02||46.70||I-80 in Salt Lake City||I-15 in North Salt Lake||1963||current|
|I‑516||6.49||10.44||SR 21/SR 204 in Savannah||SR 21 in Garden City||1985||current|
|I‑520||17.48||28.13||I-20 in Augusta, GA||I-20 in North Augusta, SC||1980||current|
|I‑220||17.62||28.36||I-20 in Shreveport||I-20 in Bossier City||1991||current|
|I-220||12.01||19.33||I-20 in Jackson||I-55 in Ridgeland||1981||current|
|I-820||35.17||56.60||I-20 in Fort Worth||I-20 / US 287 in Fort Worth||1959||current|
|I‑222||2.26||3.64||I-22 near Birmingham, AL||Interstate 422 near Birmingham, AL||proposed||—|
|I‑422||52.5||84.5||I-20/I-59/I-459/US 11 in Bessemer||I-59 in Argo||proposed||—|
|I-124||1.97||3.17||I-24 in Chattanooga||US 27 in Chattanooga||1960||current||Unsigned|
|I‑225||12.00||19.31||I-25 in Denver||I-70 in Aurora||1976||current|
|I‑126||3.68||5.92||I-26 in Columbia||US 21/US 76/US 176/US 321 in Columbia||1961||current|
|I‑526||19.26||31.00||US 17 in Charleston||I-526 Bus/US 17 in Mount Pleasant||1989||current|
|I-129||3.48||5.60||US 20/US 75/US 77 in South Sioux City, NE||I-29/US 20/US 75 in Sioux City, IA||1976||current|
|I-229||14.97||24.09||I-29 in St. Joseph||I-29/US 59/US 71 in St. Joseph||1986||current|
|I-229||11.33||18.23||I-29 in Sioux Falls||I-90 near Sioux Falls||1966||current|
|I-130||—||—||—||—||proposed||—||Proposed route in Texarkana|
|I-430||12.93||20.81||I-30/US 67 in Little Rock||I-40/US 65 in Little Rock||1980||current|
|I-530||46.65||75.08||US 65 in Pine Bluff||I-30/I-440 in Little Rock||1999||current|
|I-630||7.40||11.91||I-430 near Little Rock||I-30 in Little Rock||1985||current|
|I-235||13.78||22.18||I-35/I-80 in West Des Moines||I-35/I-80 near Des Moines||1961||current|
|I‑135||95.74||154.08||Kan. Tpk./I-35 in Wichita||I-70/US 81 in Salina||1976||current|
|I‑235||16.52||26.59||I-135/US 81 in Wichita||I-135/US 81/K-15/K-254 in Wichita||1965||current|
|I‑335||50.13||80.68||I-35/Kan. Tpk./US 50 in Emporia||I-470/Kan. Tpk. in Topeka||1987||current|
|I‑435||80.81||130.05||Beltway around Kansas City, KS and Kansas City, MO||1965||current|
|I‑635||12.67||20.39||I-35 in Overland Park, KS||I-29/US 71 in Kansas City, MO||1968||current|
|I-335||—||—||I-94 in Minneapolis||I-35W in Minneapolis||1964||1978||Cancelled|
|I-535||2.78||4.47||I-35/US 53 in Duluth, MN||US 53/WIS 35 in Superior, WI||1971||current|
|I‑235||5.36||8.63||I-35/I-40 in Oklahoma City||I-44 in Oklahoma City||1989||current|
|I-635||37.00||59.55||SH 121 in Grapevine||I-20 in Balch Springs||1959||current|
|I‑238||2.13||3.43||I-880 in San Leandro, CA||I-580/SR 238 in Castro Valley, CA||1983||current||Considered an auxiliary route of I-80 in California; there is no I-38|
|I-440||9.96||16.03||I-30/I-530 near Little Rock||I-40/AR 440 near Little Rock||2003||current|
|I-540||80.72||129.91||US 271/AR 253 near Fort Smith||US 62/US 71 in Bentonville||1965||current|
|I‑140||6.80||10.94||US 17/US 421 near Navassa||I-40/US 17 in Wilmington||2008||current|
|I‑240||9.14||14.71||I-26/I-40/US 74 near Asheville||I-40/US 74A in Asheville||1980||current|
|I‑440||16.40||26.39||I-40/US 1/US 64 near Cary||I-40 near Raleigh||1991||current|
|I‑540||26.00||41.84||I-40 near Durham||US 64/US 264 near Knightdale||1997||current|
|I‑840||5.77||9.29||I-40/I-73/US 421 in Greensboro||I-40/I-85/I-785/I-85 Bus. in Greensboro||2011||current|
|I‑240||16.22||26.10||I-44/US 62 in Oklahoma City||I-40/US 270 in Oklahoma City||1965||current|
|I-140||11.10||17.86||I-40 near Farragut||US 129 near Alcoa||1987||current|
|I-240||19.27||31.01||I-40 in Memphis||I-40 in Memphis||1970||current|
|I-440||8.00||12.87||I-40 in Nashville||I-24 in Nashville||1987||current|
|I-640||7.03||11.31||I-40 in Knoxville||I-40 in Knoxville||1982||current|
|I‑244||15.75||25.35||I-44 in Tulsa||I-44 in Tulsa||—||—|
|I‑444||2.51||4.04||I-244 in Tulsa||I-244 in Tulsa||1970||current||Unsigned|
|I-345||1.40||2.25||I-30/I-45 in Dallas, TX||US 75 in Dallas, TX||1973||current||Unsigned|
|I-555||44||71||I-55 in Turrell||AR 91 in Jonesboro||proposed||—|
|I-155||32.13||51.71||I-74 in Morton||I-55 in Lincoln||1992||current|
|I-255||30.82||49.60||I-55/I-270 in Mehlville, MO||I-270/IL 255 in Pontoon Beach, IL||1986||current|
|I-355||32.51||52.32||I-80 in New Lenox||I-290 in Itasca||1989||current|
|I-155||26.77||43.08||I-55 near Hayti, MO||US 51 at Dyersburg, TN||1980||current|
|I‑359||2.30||3.70||I-20/I-59 in southern Tuscaloosa||15th Street in downtown Tuscaloosa||1983||current|
|I‑459||32||51||I-20/I-59 in Bessemer||I-59 in Trussville||1984||current|
|I‑759||4.5||7.2||I-59 in Attalla||US-411/SR-759 in Gadsden||1986||current|
|I-164||21.24||34.18||US 41/Veterans Memorial Parkway in Evansville, IN||I-64/I-69/SR 57 near Elberfeld, IN||1990||2014||Now part of I-69|
|I-264||22.93||36.90||I-64 in Louisville||I-71 in Louisville||1956||current|
|I‑264||25||40||I-64/I-664 in Chesapeake||Parks Ave in Virginia Beach||1960||current|
|I‑464||5.66||9.11||I-64 in Chesapeake||I-264 in Norfolk||—||—|
|I‑564||2.77||4.46||SR 337||I-64 in Norfolk||1970||current|
|I‑664||20.79||33.46||I-64/I-264 in Norfolk||I-64 in Hampton||1971||current|
|I‑165||4.9||7.9||US-43 in Mobile||I-65 in Mobile||1994||current|
|I‑565||34||55||I-65/US-72/SR-20 in Decatur||US-72 in Huntsville||1991||current|
|I-265||32||51||I-64 in New Albany||SR 62/SR 265||1977||current|
|I-465||53||85||Beltway around Indianapolis||1970||current|
|I-865||5||8||I-65 near Indianapolis||I-465 near Indianapolis||2002||current|
|I-265||24.48||39.40||I-65 in Louisville||I-71 in Louisville||1977||current|
|I-469||30.83||49.62||I-69 in Fort Wayne||I-69 in Fort Wayne||1995||current|
|I-369||23.44||37.72||Future I-69/Pennyrile Parkway in Henderson||US 60 in Owensboro||proposed||—|
|I-269||64.3||103.5||I-55/I-69 in Hernando, MS||I-69 in Millington, TN||proposed||—||Currently under construction|
|I-169||—||—||Union City, TN||Martin, TN||proposed||—|
|I-369||118||190||Tenaha||Texarkana, Texas||2013||current||Partially completed in 2013|
|I‑270||5.31||8.55||I-25/US 36 at Welby||I-70/US 36 at Denver||1965||current|
|I-270||50.59||81.42||I-55/I-255 in Mehlville, MO||I-55/I-70 near Troy, IL||1956||current|
|I‑470||13.72||22.08||I-70 in Topeka||I-70/Kan. Tpk. in Topeka||1960||current|
|I‑670||2.81||4.52||I-70 in Kansas City, KS||I-70 in Kansas City, MO||1968||current|
|I-270||34.70||55.84||I-70 near Frederick||I-495 north of Bethesda||1975||current|
|I-270 Spur||2.10||3.38||I-270 east of Potomac||I-495 northwest of Bethesda||—||—|
|I-370||3.13||5.04||I-270 in Gaithersburg||MD 200 in Derwood||1988||current|
|I-170||11.17||17.98||I-64/US 40 in Richmond Heights||I-270 in Hazelwood||1956||current|
|I-470||16.72||26.91||I-49/I-435 in Kansas City, MO||I-70 in Independence, MO||1983||current|
|I‑270||54.97||88.47||Beltway around Columbus||1975||current|
|I‑470||6.69||10.77||I-70 near Blaine, OH||I-70 in Elm Grove, WV||1976||current|
|I‑670||9.37||15.08||I-70 in Columbus||I-270 near Port Columbus International Airport||2003||current|
|I‑271||40||60||I-71 near Medina, OH||I-90 in Willoughby Hills, OH||1972||current|
|I-471||5.75||9.25||I-275 near Newport, KY||I-71 in Cincinnati, OH||1981||current|
|I-172||19.69||31.69||I-72 in Quincy, IL||US 24 in Quincy, IL||1995||current|
|I-474||14.88||23.95||I-74 in Peoria, IL||I-74 in Morton, IL||1973||current|
|I‑274||—||—||—||—||proposed||—||Proposed route in Winston-Salem|
|I‑175||1.44||2.32||I-275 in St. Petersburg, FL||SR 687 in St. Petersburg, FL||1980||current|
|I‑275||63.39||102.02||I-75 near Memphis||I-75 in Wesley Chapel||1973||current|
|I‑375||1.34||2.16||I-275 in St. Petersburg||US 92 in St. Petersburg||1979||current|
|I‑475||15.8||25.4||I-75 in Macon||I-75 in Macon||1965||current|
|I‑575||30.9||49.7||I-75 in Kennesaw||SR 5 west of Nelson||1985||current|
|I‑675||11.04||17.77||I-75 in Stockbridge, GA||I-285 southeast of Atlanta, GA||1987||current|
|I-275||83.71||134.72||Beltway around Cincinnati, OH||1962||current||Runs through Indiana, Ohio and Kentucky; I-75 does not run through Indiana|
|I-275||35.01||56.34||I-75 near Monroe, MI||I-96, I-696 & M-5 in Farmington Hills||1977||current|
|I-375||1.06||1.71||BS I-375 in Detroit, MI||I-75 in Detroit, MI||1964||current|
|I-475||16.99||27.34||I-75 near Grand Blanc, MI||I-75/US 23 near Mount Morris, MI||1973||current||Runs east and north of Flint, MI|
|I-675||7.73||12.44||I-75/US 23 near Saginaw, MI||I-75/US 23 near Zilwaukee, MI||1971||current|
|I‑475||20.37||32.78||I-75 in Perrysburg||I-75 in Toledo||1971||current|
|I‑675||26.53||42.70||I-75 near Miamisburg||I-70 near Medway||1987||current|
|I-275||2.98||4.80||I-40 in Knoxville||I-75/I-640 in Knoxville||1982||current|
|I‑676||6.90||11.10||I-76/US 30 in Philadelphia||I-76 in Camden, NJ||1991||current|
|I-176||11.33||18.23||I-76/Penna Tpk. in Morgantown||US 422 near Reading||1964||current|
|I-276||32.65||52.55||I-76 in King of Prussia||Delaware River bridge (Pennsylvania-NJ state line)(current)
I-95/I-195 in Bristol Township (future)
|I-376||80.6||129.7||I-80 near Hermitage||I-76/US 22 in Monroeville||1972||current|
|I-476||132.10||212.59||I-95 near Chester, PA||I-81 near Clarks Summit, PA||1992||current||Longest Auxiliary Interstate in the country|
|I-576||—||—||—||—||proposed||—||Proposed Southern Beltway route from Pittsburgh International Airport to I-376|
|I‑277||4.41||7.10||Beltway around uptown Charlotte, NC||1981||current|
|I‑277||4.14||6.66||I-76 in Akron||I-77 in Akron||1970||current|
|I‑278||35.6||57.3||US 1/9 in Linden, New Jersey||Bruckner Interchange in Bronx, New York||1961||current|
|I-478||2.14||3.44||I-278 in Brooklyn, New York||NY 9A in Manhattan, New York||1971||current||Unsigned|
|I-678||14||23||John F. Kennedy International Airport in Queens, New York||Bruckner Interchange in Bronx, New York||1965||current|
|I-878||0.70||1.13||I-678 in Queens, New York near JFK Airport||JFK Expressway in Queens, New York near JFK Airport||1970||current||Unsigned|
|I-279||13.20||21.24||I-376/US 22/US 30 in Pittsburgh||I-79 in Franklin Park||1972||current|
|I-579||1.57||2.53||PA 885 in Pittsburgh||I-279/PA 28 in Pittsburgh||1962||current|
|I‑280||57||92||I-680/US 101 in San Jose||King Street in San Francisco||1964||current|
|I‑380||1.5||2.4||I-280 in San Bruno||US 101||1964||current|
|I‑480||—||—||—||—||1957||1968||Was to be the Embarcadero Freeway in San Francisco, CA|
|I‑580||71||114||US 101 in San Rafael||I-5 near Westley||1964||current|
|I‑680||71||114||I-280/US 101 in San Jose||I-80 in Cordelia||1955||current|
|I‑780||6.52||10.49||I-80 in Vallejo||I-680 in Benicia||1955||current|
|I‑880||45||72||I-280/SR 17 in San Jose||I-80/I-580 in Oakland||1983||current|
|I‑980||2.02||3.25||I-880 in Downtown Oakland||I-580/SR 24 in Oakland||1981||current|
|I-180||13.19||21.23||IL 26/IL 71 in Hennepin, Illinois||I-80 near Princeton, Illinois||1969||current|
|I-280||26.98||43.42||I-80 near Davenport, IA||I-74/I-80 near Colona, IL||1990||current|
|I-380||73.05||117.56||I-80 near Iowa City||US 218 in Waterloo||1985||current||Connects Cedar Rapids with I-80|
|I-480||4.90||7.89||I-80/US 75 in Omaha, NE||I-29/US 6 in Council Bluffs, IA||1966||current|
|I-680||42.86||68.98||I-80 in Omaha, NE||I-80 near Neola, IA||1966||current|
|I-180||3.47||5.58||US 34 (9th St. / 10th St.) in Lincoln||I-80 / US 34 / US 77 in Lincoln||1964||current|
|I-580||1.6||2.6||I-480 in Omaha||Lake Street in Omaha||1976||1982||Now part of US 75|
|I‑580||34.50||55.52||Fairview Drive in Carson City, NV||I-80 in Reno, NV||2012||current|
|I‑280||17.85||28.73||I-80 in Parsippany-Troy Hills||I-95/NJ Tpk. in Kearny||1958||current|
|I‑280||12.41||19.97||I-75 in Toledo, OH||I-80/I-90/Ohio Tpk. in Lake Township, OH||1959||current|
|I‑480||41.77||67.22||I-80/Ohio Tpk. in North Ridgeville, OH||I-80/Ohio Tpk. in Streetsboro, OH||1998||current|
|I‑680||16.43||26.44||I-76/Ohio Tpk. in North Lima, OH||I-80/SR 11 near Mineral Ridge, OH||—||—|
|I-180||28.85||46.43||US 15/US 220 in Williamsport, PA||I-80/PA 147 near Milton, PA||1984||current|
|I-380||24.76||39.85||I-80 in Tunkhannock Township. PA||I-81/I-84/US 6 in Dunmore, PA||1973||current|
|I-180||1.09||1.75||I-80 in Cheyenne, WY||I-80 Bus/US 30 in Cheyenne, WY||1984||current||Not built to Interstate Highway standards|
|I-481||15.04||24.20||I-81 in Onondaga, NY||I-81/NY 481 in North Syracuse||1970||current|
|I-781||4.9||7.9||I-81 in Pamelia, NY||Fort Drum main gate in Le Ray, NY||2012||current|
|I‑381||1.70||2.74||SR 381 in Bristol||I-81 in Bristol||1961||current|
|I‑581||6.35||10.22||US 220/SR 24 in Roanoke||I-81 near Hollins||1950||current|
|I‑182||15.19||24.45||I-82/US 12 near Richland||US 12/US 395 in Pasco||1986||current|
|I-283||2.91||4.68||I-76/Penna Tpk. near Highspire||I-83/US 322/Capital Beltway near Harrisburg||1972||current|
|I-384||8.53||13.73||I-84/US 6 in East Hartford||US 6/US 44 in Bolton||1984||current|
|I-684||28.4||45.7||I-287 near White Plains, NY||NY 22 near Brewster, NY||1974||current||Also crosses into Connecticut|
|I-184||3.62||5.83||I-84 in Boise, ID||US 20/US 26||1990||current|
|I‑685||14.44||23.24||I-65 in downtown Montgomery, AL||I-85 in Montgomery, AL||proposed||—|
|I‑185||49.30||79.34||US 27/US 280/SR 520 in Columbus||I-85 near LaGrange||1979||current|
|I‑285||63.98||102.97||Beltway around Atlanta, GA||1969||current|
|I‑985||24.04||38.69||I-85 near Buford, GA||SR 369 near Gainesville||1985||current|
|I‑285||23.00||37.01||I-85/I-85 Bus./US 29/US 52/US 70 near Lexington, NC||I-40/US 52/US 311/NC 8 in Winston-Salem, NC||proposed||—|
|I‑485||67.6||108.8||Beltway around Charlotte, NC||1988||current|
|I‑785||2.21||3.56||I-40/I-85/I-840/I-85 Bus. in Greensboro, NC||US 70 in Greensboro, NC||2013||current|
|I‑185||17.70||28.49||I-385 near Mauldin, SC||US 29 in Greenville, SC||1955||current|
|I‑385||42.16||67.85||I-26 near Clinton, SC||US 276 in Greenville, SC||1962||current|
|I‑585||2.25||3.62||US 176/US 221/SC 9 in Spartanburg, SC||I-85 Bus./US 176 near Spartanburg, SC||1962||current|
|I‑785||7.20||11.59||US 29/US 58/US 29 Bus. in Danville, VA||US 29/US 58/US 360/US 58 Bus. in Danville, VA||proposed||—|
|I‑287||98.65||158.76||I-95/NJ Tpk. in Edison, NJ||I-95 in Rye, NY||1961||current|
|I-587||1.21||1.95||I-87/Thruway/NY 28 in Kingston, NY||NY 28/NY 32 in Kingston, NY||1960||current|
|I-787||9.55||15.37||I-87/Thruway in Albany, NY||NY 7 in Green Island, NY||1968||current|
|I‑189||1.49||2.40||US 7 in South Burlington, VT||I-89 in South Burlington||1980||current|
|I-190||3.07||4.94||O'Hare International Airport in Chicago, IL||I-90 in Chicago, IL||1978||current|
|I-290||29.84||48.02||I-90/IL 53 in Rolling Meadows, IL||I-90/I-94 / Congress Parkway in Chicago, IL||1972||current|
|I‑190||19.26||31.00||I-290 in Worcester, MA||Route 2 in Leominster, MA||1983||current|
|I‑290||20.16||32.44||I-90/Mass Pike/I-395 in Auburn, MA||I-495 in Marlborough, MA||1970||current|
|I-190||28.34||45.61||I-90/Thruway in Cheektowaga, NY||Highway 405 at Lewiston, NY||1959||current|
|I-290||9.80||15.77||I-190 in Tonawanda, NY||I-90/Thruway in Williamsville, NY||1964||current|
|I-390||75.86||122.08||I-86/NY 17 in Avoca, NY||I-490 in Gates, NY||1973||current|
|I-490||37.40||60.19||I-90/Thruway in Bergen, NY||I-90/Thruway in Victor, NY||1970||current|
|I-590||5.07||8.16||I-390 in Brighton, NY||I-490/NY 590 in Rochester, NY||1980||current|
|I-690||14.19||22.84||I-90/Thruway/NY 690 in Van Buren, NY||I-481 in East Syracuse, NY||1962||current|
|I-790||2.41||3.88||I-90/Thruway in Deerfield, Ny||NY 5A/NY 55 in Utica, NY||1961||current|
|I-890||9.45||15.21||I-90/Thruway in Rotterdam, NY||I-90/Thruway in Guilderland, NY||1962||current|
|I-990||6.35||10.22||I-290 in Amherst, NY||NY 263 near Lockport, NY||1985||current|
|I‑490||2.43||3.91||I-71/I-90 in Cleveland, OH||East 55th Street in Cleveland, OH||1990||current|
|I-190||2||3||I-90 in Rapid City, SD||US 16 in Rapid City, SD||—||—|
|I-291||6.40||10.30||I-91 in Windsor, CT||I-84 in Manchester, CT||1994||current|
|I-691||8.92||14.36||I-84 at the Southington-Cheshire town line, CT||I-91 in Meriden, CT||1988||current|
|I‑291||5.44||8.75||I-91 in Springfield, MA||I-90/Mass Pike in Chicopee, MA||1972||current|
|I‑391||4.86||7.82||I-91 in Chicopee, MA||High Street in Holyoke, MA||1970||current|
|I‑293||11.43||18.39||I-93/NH 101 in Manchester, NH||I-93/Everett Tpke in Hooksett, NH||2008||current|
|I‑393||4.50||7.24||I-93 in Concord, NH||NH 9 in Pembroke, NH||1979||current|
|I-294||53.42||85.97||I-80/I-94 in South Holland, Illinois||I-94 in Deerfield, Illinois||1968||current|
|I-194||3.42||5.50||I-94 in Battle Creek. MI||M-66 in Battle Creek, MI||1961||current|
|I-394||9.50||15.29||I-494/US 12 in Minnetonka, MN||4th Street in Minneapolis, MN||1991||current|
|I-494||43||69||I-94/I-694 in Maple Grove, MN||I-94/I-694 in Woodbury, MN||1985||current||Western and southern half of the Minneapolis–St. Paul beltway|
|I-694||31||50||I-94/I-494 in Maple Grove, MN||I-94/I-494 in Woodbury, MN||1970||current||Northern and eastern half of the Minneapolis–St. Paul beltway|
|I‑194||1.7||2.7||McKenzie Drive near Bismarck, ND||I-94 near Mandan, ND||—||—||Unsigned|
|I-794||3.75||6.04||I-43/I-94 in Milwaukee, WI||WIS 794 in Milwaukee, WI||1980||current|
|I-894||9.30||14.97||I-94 in Milwaukee, WI||I-43/I-94 in Milwaukee, WI||1966||current|
|I-395||66.63||107.23||I-95 in East Lyme, CT||I-90 in Auburn, MA||1983||current|
|I‑295||73.50||118.29||I-95/I-495 in New Castle, DE||I-95/US 1 in Lawrence Township, NJ (current)
I-95 / I-276 in Bristol Township, PA (future)
|I‑495||11.47||18.46||I-95/I-295 in Newport, DE||I-95 in Claymont, DE||1977||current|
|I‑295||8.05||12.96||I-95/I-495 near Forest Heights, MD||I-695 in Washington, DC||1964||current|
|I‑395||13||21||I-95/I-495 in Springfield, VA||US 50 in Washington, DC||1977||current||Original route of I-95 that was proposed to continue through Washington, DC|
|I‑495||64.0||103.0||—||—||1961||current||Capital Beltway; runs through Virginia, Maryland and a small sliver of Washington, DC, over the Wilson Bridge|
|I‑695||1.39||2.24||I-395 in Washington, DC||I-295 in Washington, DC||1958||current|
|I‑195||4.42||7.11||I-95/SR 112 in Miami, FL||SR 905 in Miami Beach, FL||1961||current|
|I‑295||60.86||97.94||Beltway around Jacksonville||1970||current|
|I‑395||1.29||2.08||I-95||MacArthur Causeway at Watson Island, Miami, FL||1971||current|
|I‑595||12.86||20.70||I-75/SR 869 in Weston, FL||US 1 in Fort Lauderdale, FL||1990||current|
|I‑795||4.5||7.2||Interstate 95 south of Jacksonville||I-295 in Jacksonville||proposed||—||Currently under construction; partially open as SR 9B but not yet signed as I-795|
|I‑195||1.55||2.49||I-95/Maine Tpk. in Saco, ME||SR 5 in Saco, ME||1980||current|
|I‑295||52||84||I-95/Maine Tpk. in Scarborough, ME||I-95/Maine Tpk. in Gardiner, ME||1960||current|
|I‑395||4.99||8.03||I-95/US 2/SR 100 in Bangor, ME||US 1A in Brewer, ME||2008||current|
|I‑495||3.7||6.0||I-95/Maine Tpk. in Portland, ME||I-295/US 1 in Falmouth, ME||2004||current||Unsigned|
|I-195||4.88||7.85||I-95/MD 166 near Catonsville, MD||Baltimore-Washington International Airport||1990||current|
|I-395||1.95||3.14||I-95 in South Baltimore, MD||West Pratt Street in Baltimore, MD||1981||current|
|I-595||19.97||32.14||I-95/I-495/US 50 near Washington, DC||US 50/US 301/MD 70 in Annapolis, MD||2011||current||Unsigned designation for US 50|
|I-695||51.46||82.82||Beltway around Baltimore||1958||current|
|I-795||8.99||14.47||I-695 in Pikesville, MD||MD 140 in Reisterstown, MD||1985||current|
|I-895||11.44||18.41||I-95 near Elkridge, MD||I-95 in Baltimore, MD||1979||current|
|I‑295||8.05||12.96||I-95/I-495 near Forest Heights, MD||I-695 in Washington, DC||1964||current|
|I‑195||40.1||64.5||I-95 in Providence, RI||I-495/Route 25 in Wareham, MA||1958||current|
|I‑295||26.58||42.78||I-95 in Warwick, RI||I-95 in Attleboro, MA||1969||current|
|I‑495||120.74||194.31||I-195/Route 25 in Wareham, MA||I-95 in Salisbury, MA||1957||current|
|I‑695||—||—||I-93 in Roxbury, Boston||I-93 in Charlestown, Boston||1955||1971||Cancelled; was to have been built in connection with a planned alignment of I-95 through downtown Boston|
|I‑195||34.17||54.99||I-295 in Hamilton Township, NJ||Route 34 in Wall Township, NJ||1968||current|
|I-295||9.10||14.65||Hillside Avenue (NY 25)/NY 24 in Queens, NY||Bruckner Interchange in the Bronx, NY||1970||current|
|I-495||71.02||114.30||Queens Midtown Tunnel in Manhattan, NY||CR 58 in Riverhead, NY||1958||current|
|I-695||1.3||2.1||I-95 in the Bronx, NY||I-295 in the Bronx, NY||1986||current|
|I-895||1.12||1.80||I-278 in the Bronx, NY||I-95 in the Bronx, NY||1970||current|
|I‑295||—||—||—||—||proposed||—||Planned route around the west side of Fayetteville, NC|
|I‑495||4.09||6.58||I-440/US 64/US 64 Bus in Raleigh, NC||I-540/US 64/US 264 in Knightdale, NC||2013||current|
|I‑795||25.41||40.89||US 70/US 117 in Goldsboro, NC||I-95/US 264 in Wilson, NC||2007||current|
|I‑195||3.50||5.63||SR 195 in Richmond, VA||I-64/I-95 in Richmond, VA||1970||current|
|I‑295||52.75||84.89||I-95 near Petersburg, VA||I-64 near Short Pump, VA||1980||current|
|I-196||—||—||US 31 in Norton Shores, MI||I-96/US 16 in Grand Rapids, MI||1959||1963||Now the western end of I-96|
|I-196||81||130||I-94/US 31 near Benton Harbor, MI||I-96/M-37 in Grand Rapids, MI||1963||current|
|I-296||3.43||5.52||I-196 in Grand Rapids, MI||I-96/M-37 in Walker, MI||1962||current||Unsigned since 1979|
|I-496||11.78||18.96||I-69/I-96 near Lansing, MI||I-96 and US 127 near Lansing, MI||1970||current|
|I-696||29.24||47.06||I-96/I-275 & M-5 in Novi, MI||I-94 in Roseville, MI||1989||current|
- 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.
- DeSimone, Tony (October 31, 2002). "FHWA Route Log and Finder List: Interstate Route Numbering". Federal Highway Administration. Retrieved February 3, 2008.
- "Signs Go Up Along North Carolina’s Newest Interstate, I-495". North Carolina Department of Transportation. 25 April 2014. Retrieved 22 October 2014.
- DeSimone, Tony (October 31, 2002). "Table 2: Auxiliary Routes of the Dwight D. Eisenhower National System Of Interstate and Defense Highways as of October 31, 2002". Route Log and Finder List. Federal Highway Administration. Retrieved June 2, 2007.
- Tabb, John R. (December 8, 1990). "Report of the Special Committee on U.S. Route Numbering to the Executive Committee" (PDF) (Report). Phoenix, AZ: American Association of State Highway and Transportation Officials.