List of intrastate Interstate Highways

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Dwight D. Eisenhower National System of Interstate and Defense Highways
Intrastate Interstate Highways in the 48 contiguous states highlighted in red
System information
Formed: June 29, 1956[1]
Highway names
Interstates: Interstate X (I-X)
System links

There are several intrastate Interstate Highways; that is, Interstate Highways that are each located entirely within one U.S. state. (The name "Interstate" refers to the entire system and not the individual roads.)


Within the contiguous 48 states[edit]

This list includes only primary Interstate highways (those with route numbers less than 100). Most (but not all) three digit Interstates are intrastate. Among the three digit interstates, examples of non-intrastate routes include I-435 in Kansas City, Missouri and Kansas City, Kansas and I-535 which crosses from Duluth into Superior.

Interstate Highway State Route Length (mi)[2] Length (km) Notes
Interstate 2 Texas Mission (US 83) to Harlingen (I-69E /US 77) 46.8 75.3
Interstate 4 Florida Tampa (I-275) to Daytona Beach (I-95) 132.3 212.9
Interstate 12 Louisiana Baton Rouge (I-10) to Slidell (I-10/I-59) 85.6 137.8
Interstate 16 Georgia Macon (I-75) to Savannah (Montgomery Street) 166.8 268.4
Interstate 17 Arizona Phoenix (I-10) to Flagstaff (I-40) 145.8 234.6
Interstate 19 Arizona Nogales (Mexican border) to Tucson (I-10) 63.4 102.0 Interstate 19 reaches the Mexican border but does not cross any state lines. Onward connection (via Federal 15 to Mexico City) is discontinuous and depends on surface roads at the border.
Interstate 27 Texas Lubbock (US 87) to Amarillo (I-40/US 60/US 87/US 287) 124.1 199.7
Interstate 37 Texas Corpus Christi (US 181) to San Antonio (I-35) 143.0 230.1
al= Interstate 43 Wisconsin Beloit (I-39/I-90) to Green Bay (US 41/US 141) 191.6 308.4
Interstate 45 Texas Galveston (SH-124) to Dallas (I-30/US 67) 284.9 458.5 The only two-digit Interstate ending in 5 or 0 to be an intrastate Highway. Such numbers are supposed to be signed to major interstates, which is why it is unusual that this one is intrastate.
Interstate 73 North Carolina Ellerbe (US 220) to Greensboro (I-40/I-85)[3] 56.7 91.2 Planned to reach Michigan and South Carolina
Interstate 86 (west) Idaho Heyburn (I-84/US 30) to Pocatello (I-15) 62.9 101.2
Interstate 87 New York New York City (I-278) to Champlain (Canadian border) 333.5 536.7 The longest intrastate Interstate highway, Interstate 87 reaches the Canadian border (continuing as Quebec Autoroute 15 through Montréal to Sainte-Agathe-des-Monts in the Laurentian Mountains), but it does not cross any state lines.
Interstate 88 (west) Illinois Silvis (I-80) to Hillside (I-290) 140.6 226.3
Interstate 88 (east) New York Binghamton (I-81) to Schenectady (I-90) 117.8 189.6
Interstate 96 Michigan Norton Shores (US 31) to Detroit (I-75) 192.1 309.2
Interstate 97 Maryland Annapolis (US 50) to Baltimore (I-695/I-895) 17.6 28.3 Currently the shortest two-digit interstate highway in the country, the only two-digit interstate highway on the U.S. mainland located entirely within one county, and the only two-digit interstate highway on the U.S. mainland that does not connect to any other two-digit interstate highways.

Additionally, there are six Interstate highways that are almost entirely intrastate:

  • Interstate 57 is located almost entirely in Illinois, but it has a relatively short section in Missouri, compared to its long journey through the "Land of Lincoln". I-57 is 386 miles (621 km) in length, with twenty-two miles (35 km) found within Missouri.
  • Interstate 66 is located almost entirely in Virginia, but it has quite a short section in the District of Columbia. I-66 is 75 miles (121 km) in length, with one-half mile (0.8 km) in D.C.
  • Interstate 72 is located almost entirely in Illinois, but it has a very short section in Missouri. I-72 is 184 miles (296 km) in length, with two miles (3.2 km) in Missouri.
  • Interstate 74 has multiple discontinuous segment entirely within North Carolina, seeing as none of them cross any state line, though other states have instances of this route too.
  • Interstate 76 (western section) is located almost entirely in Colorado, but it has a very short section in Nebraska that connects Interstate 80. I-76 is 186 miles (299 km) in length, with less than three miles (4.8 km) in Nebraska.
  • Interstate 82 is located almost entirely in Washington, but it has a short section in Oregon that connects to Interstate 84. I-82 is 144 miles (232 km) in length, with just about eleven miles (18 km) in Oregon.
  • Interstate 86 (eastern section) is located almost entirely in New York, but it has a short section in Pennsylvania that connects to Interstate 90. I-86 is 177 miles (285 km) in length (in the process of being expanded to 380 mi or 610 km), with less than seven miles (11 km) in Pennsylvania.

Outside of the contiguous 48 states[edit]

As Alaska and Hawaii do not share land borders with any other U.S. state, their Interstate highways are all located fully within their respective state's boundaries. Puerto Rico is not a state; however, it also has highways funded by the Federal Government as Interstate highways.

Signed Interstates[edit]

H-1, H-2, and H-3 stand for Hawaii-1, Hawaii-2, and Hawaii-3, respectively. These freeways are part of the Interstate Highway System and are thus called Interstate highways. These are all located on the heavily populated island of Oahu, and there are none on the other islands.

Interstate Highway Route Length (mi)[2] Length (km)
Interstate H-1 Kapolei, HI (Route 93) to Honolulu, HI (Route 72) 27.2 43.8
Interstate H-2 Pearl City, HI (H-1) to Wahiawā, HI (Route 99) 8.3 13.4
Interstate H-3 Hālawa, HI (H-1) to Marine Corps Base Hawaii 15.3 24.6

Unsigned Interstates[edit]

Interstate highways in Alaska and Puerto Rico are not signed as Interstate highways, and are designated as such primarily for purposes of Federal funding. Interstates A-1 through A-4 are located in Alaska, and Interstates PRI-1 through PRI-3 are located in Puerto Rico. These highways are not required to meet interstate standards, and as a result, most portions of these interstate highways are not grade-separate freeways. Freeways in Puerto Rico are primarily toll roads that are not funded through the Eisenhower Interstate System. Very few freeways exist in Alaska; they are located primarily near Anchorage, Fairbanks, and Wasilla.

Interstate Highway Route Length (mi)[2] Length (km)
Interstate A-1 Anchorage, AK (A-3) to Canadian border 408.2 656.9
Interstate A-2 Tok, AK (A-1) to Fairbanks (A-4) 202.2 325.4
Interstate A-3 Anchorage, AK (A-1) to Soldotna 148.1 238.3
Interstate A-4 Palmer, AK (A-1) to Fairbanks (A-2) 323.7 520.9
Interstate PRI-1 Ponce, PR (PRI-2) to San Juan (PRI-2) 71.1 114.4
Interstate PRI-2 Ponce, PR (PRI-1) to San Juan (PRI-3) 138.1 222.3
Interstate PRI-3 San Juan, PR (PRI-2) to Ceiba 40.6 65.3

See also[edit]

References[edit]

  1. ^ 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. 
  2. ^ a b c DeSimone, Tony (January 19, 2012). "Table 1: Main 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 March 28, 2012. 
  3. ^ Obenberger, Jon; DeSimone, Tony (March 14, 2012). "Dwight D. Eisenhower National System of Interstate and Defense Highways: Interstate System Facts". Federal Highway Administration. Retrieved March 28, 2012.