Primary Interstate Highways are the major interstate highways of the United States and have a one or two-digit route number. Even (2, 4, 6, 8, or 0) route numbers are given to east/west routes, with the smaller numbered routes in the south (I-10) and bigger numbered routes in the north (I-90). Similarly, odd (1, 3, 5, 7, or 9) route numbers are given to north/south routes, with the smaller numbered routes in the west (I-5) and the bigger numbered routes in the east (I-95).
There are five sets of numbers that are used more than once throughout the system; the highways whose numbers are used more than once are separated by big distances to avoid confusion. Below, these are made separate from each other by West and East.
Three-digit Interstates are spur or loop Interstates that usually are in big cities and areas outside of cities. The last two digits of a three-digit Interstate are always the number of the route it is related to. If the first digit is odd (1, 3, 5, 7, or 9), the Interstate is usually a spur route while if the first digit is even (2, 4, 6, 8, or 0), the Interstate is usually a loop route.
There are 66 primary Interstates that are in the table below, with 43 of them having three-digit routes. The lengths in the table are as of October 31, 2002.
Routes ending in 0 or 5 are marked in green.
Interstate |
Route, States Served & Associated routes (* not signposted as interstates) (sort by number of states served) |
Length[1] (mi.) |
---|---|---|
I-4 | Tampa, Florida (I-275) to Daytona Beach, Florida (I-95) Florida Intrastate Interstate Associated routes: none |
132.30 |
I-5 | San Ysidro, California (Mexico and MX-1) to Blaine, Washington (Canada and BC 99) 3 States Served: CA, OR, WA Associated routes: I-105, I-205, I-305*, I-405, I-505, I-605, I-705, I-805 |
1,381.29 |
I-8 | San Diego, California (Sunset Cliffs Blvd.) to Casa Grande, Arizona (I-10) 2 States Served: CA, AZ Associated routes: none |
348.25 |
I-10 | Santa Monica, California (CA-1) to Jacksonville, Florida (I-95) 8 States Served: CA, AZ, NM, TX, LA, MS, AL, FL Associated routes: I-110, I-210, I-310, I-410, I-510, I-610, I-710, I-910* |
2,460.34 |
I-12 | Baton Rouge, Louisiana (I-10) to Slidell, Louisiana (I-10 / I-59) Louisiana Intrastate Interstate Associated routes: none |
85.59 |
I-15 | San Diego, California (I-8/CA-15) to Sweetgrass, Montana (Canada and Hwy 4) 6 States Served: CA, NV, AZ, UT, ID, MT Associated routes: I-115, I-215, I-315*, I-515 |
1,433.52 |
I-16 | Macon, Georgia (I-75) to Savannah, Georgia (Montgomery St.) Georgia Intrastate Interstate Associated route: I-516 |
166.81 |
I-17 | Phoenix, Arizona (I-10) to Flagstaff, Arizona (AZ-89A) Arizona Intrastate Interstate Associated routes: none |
145.76 |
I-19 | Nogales, Arizona (Mexico and MX-15) to Tucson, Arizona (I-10) Arizona Intrastate Interstate Associated routes: none |
63.35 |
I-20 | Kent, Texas (I-10) to Florence, South Carolina (I-95) 6 States Served: TX, LA, MS, AL, GA, SC Associated routes: I-220, I-520, I-820 |
1,539.38 |
I-22 | Memphis, Tennessee (I-55 & I-40) to Birmingham, Alabama (I-65/US 31) 2 States Served: Mississippi, Alabama. Planned: Tennessee Associated route: I-422 (planned) |
213.0 |
I-24 | Pulley's Mill, Illinois (I-57) to Chattanooga, Tennessee (I-75) 4 States Served: Illinois, Kentucky, Tennessee, Georgia Associated route: I-124 |
316.36 |
I-25 | Las Cruces, New Mexico (I-10) to Buffalo, Wyoming (I-90) 3 States Served: New Mexico, Colorado, Wyoming Associated route: I-225 |
1,062.77 |
I-26 | Kingsport, Tennessee (US-11W) to Charleston, South Carolina (US-17) 3 States Served: Tennessee, North Carolina, South Carolina Associated routes: I-126, I-526 |
346[2] |
I-27 | Lubbock, Texas (US-87 and Loop 289) to Amarillo, Texas (I-40) Texas Intrastate Interstate Associated routes: none |
124.13 |
I-29 | Kansas City, Missouri (I-35 & I-70) to Pembina, North Dakota (Canada and US 81 and PTH 29) 4 States Served: Missouri, Iowa, South Dakota, North Dakota Associated routes: I-129, I-229 |
755.51 |
I-30 | Fort Worth, Texas (I-20) to North Little Rock, Arkansas (I-40) 2 States Served: Texas, Arkansas Associated routes: I-430, I-530, I-630 |
366.76 |
I-35 | Laredo, Texas (Mexico) to Duluth, Minnesota (MN-61) 6 States Served: TX, OK, KS, MO, IA, MN Associated routes: I-35E, I-35W, I-135, I-235, I-335, I-435, I-535, I-635 |
1,568.38 |
I-37 | Corpus Christi, Texas (US-181) to San Antonio, Texas (I-35) Texas Intrastate Interstate Associated routes: none |
143.00 |
I-39 | Normal, Illinois (I-55) to Wausau, Wisconsin (WIS 29 & US-51) 2 States Served: Illinois, Wisconsin Associated routes: none |
306.14 |
I-40 | Barstow, California (I-15) to Wilmington, North Carolina (NC-132) 8 States Served: CA, AZ, NM, TX, OK, AR, TN, NC Associated routes: I-140, I-240, I-440, I-540, I-840 |
2,554.10 |
I-43 | Beloit, Wisconsin (I-39 and I-90) to Howard, Wisconsin (US-41 and US-141) Wisconsin Intrastate Interstate Associated routes: none |
191.55 |
I-44 | Wichita Falls, Texas (US-277, US-281, and US-287) to St. Louis, Missouri (I-55) 3 States Served: Texas, Oklahoma, Missouri Associated routes: I-244, I-444* |
633.79 |
I-45 | Galveston, Texas (TX-87) to Dallas, Texas (I-30) Texas Intrastate Interstate Associated route: I-345* |
284.91 |
I-49 | Lafayette, Louisiana (I-10) to Shreveport, Louisiana (I-20) Louisiana Intrastate Interstate Associated routes: none |
208.25 |
I-55 | Laplace, Louisiana (I-10) to Chicago, Illinois (US-41, Lake Shore Drive) 6 States Served: LA, MS, TN, AR, MO, IL Associated routes: I-155, I-255, I-355 |
964.25 |
I-57 | Miner, Missouri (I-55) to Chicago, Illinois (I-94) 2 States Served: Missouri, Illinois Associated routes: none |
386.12 |
I-59 | Slidell, Louisiana (I-10 & I-12) to Lookout Mountain, Georgia (I-24) 4 States Served: Louisiana, Mississippi, Alabama, Georgia Associated routes: I-359, I-459, I-759 |
445.23 |
I-64 | Wentzville, Missouri (I-70) to Chesapeake, Virginia (I-264 & I-664) 6 States Served: MO, IL, IN, KY, WV, VA Associated routes: I-164, I-264, I-464, I-564, I-664 |
953.74 |
I-65 | Mobile, Alabama (I-10) to Gary, Indiana (I-90) 4 States Served: Alabama, Tennessee, Kentucky, Indiana Associated routes: I-165, I-265, I-465, I-565, I-865 |
887.30 |
I-66 | Middletown, Virginia (I-81) to Washington, D.C. (US-29) 2 States Served: Virginia, District of Columbia Associated routes: none |
76.28 |
I-68 | Morgantown, West Virginia (I-79) to Hancock, Maryland (I-70) 2 States Served: West Virginia, Maryland Associated routes: none |
113.15 |
I-69 | Indianapolis, Indiana (I-465) to Port Huron, Michigan (Canada and Hwy 402) 4 States Served: MS, TN, IN, MI. 5 Planned: TX, LA, AR, MS, KY Associated route: I-469 I-269 future, I-369 planned |
355.81 |
I-70 | Cove Fort, Utah (I-15) to Baltimore, Maryland (I-695) 10 States Served: UT, CO, KS, MO, IL, IN, OH, WV, PA, MD Associated routes: I-170, I-270, I-370, I-470, I-670 |
2,153.13 |
I-71 | Louisville, Kentucky (I-64) to Cleveland, Ohio (I-90) 2 States Served: Kentucky, Ohio Associated routes: I-271, I-471 |
345.57 |
I-72 | Hannibal, Missouri (US-61) to Champaign, Illinois (I-57) 2 States Served: Missouri, Illinois Associated route: I-172 |
179.29 |
I-73 | Candor, North Carolina (US-220) to Greensboro, North Carolina (I-40 & I-85) North Carolina Intrastate Interstate Associated routes: none |
12.27 |
I-74 | West Bettendorf, Iowa (I-80) to Cincinnati, Ohio (I-75) 7 States Served: IA, IL, IN, OH, WV, VA, NC Associated route: I-474 |
416.71 |
I-74 | East Cana, Virginia (I-77) to Mount Airy, North Carolina (US-52) 2 States Served: VA, NC. Planned: WV Associated routes: none |
12.10 |
I-75 | Hialeah, Florida (FL-826) to Sault Ste. Marie, Michigan (Canada) 6 States Served: FL, GA, TN, KY, OH, MI Associated routes: I-175, I-275, I-375, I-475, I-575, I-675 |
1,786.47 |
I-76 | West Denver, Colorado (I-70) to Big Springs, Nebraska (I-80) 2 States Served: Colorado, Nebraska Associated routes: none |
187.34 |
I-76 | East Westfield Center, Ohio (I-71) to Camden, New Jersey (I-295) 3 States Served: Ohio, Pennsylvania, New Jersey Associated routes: I-176, I-276, I-376, I-476, I-676 |
434.36 |
I-77 | Columbia, South Carolina (I-26) to Cleveland, Ohio (I-90) 5 States Served: South Carolina, North Carolina, Virginia, West Virginia, Ohio Associated routes: I-277 |
610.10 |
I-78 | Union Twp., Pennsylvania (I-81) to New York, New York 3 States Served: Pennsylvania, New Jersey, New York Associated routes: I-278, I-478*, I-678, I-878* |
143.56 |
I-79 | Charleston, West Virginia (I-77) to Erie, Pennsylvania (PA-5) 2 States Served: West Virginia, Pennsylvania Associated routes: I-279, I-579 |
343.24 |
I-80 | San Francisco, California (U.S. Route 101) to Fort Lee, New Jersey (I-95) 11 States Served: CA, NV, UT, WY, NE, IA, IL, IN, OH, PA, NJ Associated routes: I-180, I-280, I-380, I-480, I-580, I-680, I-780, I-880, I-980 |
2,899.54 |
I-81 | Dandridge, Tennessee (I-40) to Fisher's Landing, New York (Canada) 6 States Served: TN, VA, WV, MD, PA, NY Associated routes: I-181, I-381, I-481, I-581 |
854.89 |
I-82 | Ellensburg, Washington (I-90) to Hermiston, Oregon (I-84) 2 States Served: Washington, Oregon Associated route: I-182 |
143.58 |
I-83 | Baltimore, Maryland to Harrisburg, Pennsylvania (I-81) 2 States Served: Maryland, Pennsylvania Associated route: I-283 |
85.3 |
I-84 | West Portland, Oregon (I-5) to Echo, Utah (I-80) 3 States Served: Oregon, Idaho, Utah Associated route: I-184 |
769.62 |
I-84 | East Scranton, Pennsylvania (I-81) to Sturbridge, Massachusetts (I-90) 4 States Served: Pennsylvania, New York, Connecticut, Massachusetts Associated routes: I-384, I-684 |
232.4 |
I-85 | Montgomery, Alabama (I-65) to Petersburg, Virginia (I-95) 5 States Served: Alabama, Georgia, South Carolina, North Carolina, Virginia Associated routes: I-185, I-285, I-385, I-485, I-585, I-785, I-985 |
668.75 |
I-86 | West Heyburn, Idaho (I-84) to Pocatello, Idaho (I-15) Idaho Intrastate Interstate Associated routes: none |
62.85 |
I-86 | East Erie, Pennsylvania (I-90) to Elmira, New York (NY-17) 2 States Served: Pennsylvania, New York Associated routes: none |
183.56 |
I-87 | New York, New York (I-278) to Champlain, New York (Canada) New York Intrastate Interstate Associated routes: I-287, I-587, I-787 |
333.49 |
I-88 | West Barstow, Illinois (I-80) to Chicago, Illinois (I-290) Illinois Intrastate Interstate Associated routes: none |
140.6 |
I-88 | East Binghamton, New York (I-81) to Schenectady, New York (I-90) New York Intrastate Interstate Associated routes: none |
117.75 |
I-89 | Bow, New Hampshire (I-93) to Highgate Springs, Vermont (Canada) 2 States Served: New Hampshire, Vermont Associated route: I-189 |
191.12 |
I-90 | Seattle, Washington (WA-519) to Boston, Massachusetts (MA-1A) 13 States Served: WA, ID, MT, WY, SD, MN, WI, IL, IN, OH, PA, NY, MA Associated routes: I-190, I-290, I-390, I-490, I-590, I-690, I-790, I-890, I-990 |
3,020.54 |
I-91 | New Haven, Connecticut/North Haven, Connecticut (I-95) to Derby Line, Vermont (Canada) 3 States Served: Connecticut, Massachusetts, Vermont Associated routes: I-291, I-391, I-691 |
290.37 |
I-93 | Canton, Massachusetts (I-95) to St. Johnsbury, Vermont (I-91) 3 States Served: Massachusetts, New Hampshire, Vermont Associated routes: I-293, I-393 |
189.95 |
I-94 | Billings, Montana (I-90) to Port Huron, Michigan (Canada) 7 States Served: MT, ND, MN, WI, IL, IN, MI Associated routes: I-194, I-294, I-394, I-494, I-694, I-794, I-894 |
1,585.20 |
I-95 | Miami, Florida (US-1) to Houlton, Maine (Canada) 15 States Served: FL, GA, SC, NC, VA, MD, DE, PA, NJ, NY, CT, RI, MA, NH, ME Associated routes: I-195, I-295, I-395, I-495, I-595, I-695, I-795, I-895 |
1,925.74 |
I-96 | Muskegon, Michigan (US-31) to Detroit, Michigan (I-75) Michigan Intrastate Interstate Associated routes: I-196, I-296*, I-496, I-696 |
192.06 |
I-97 | Annapolis, Maryland (US-50) to Baltimore, Maryland (I-695) Maryland Intrastate Interstate Associated routes: none |
17.62 |
I-99 | Bedford, Pennsylvania (I-76) to Bellefonte, Pennsylvania (I-80) Pennsylvania Intrastate Interstate Associated routes: none |
85.0 |
Interstate Highways are not only in the48 states of the United States that border, but there are also Interstates in Hawaii, Alaska, and Puerto Rico.
The Interstate Highways in the island of Oʻahu, Hawaii are signed with the normal Interstate shield, with the letter "H-" added before the number. They are fully controlled-access routes built to the same standards as the Interstate routes in the main part of the United States.
Interstate | Route | Length (miles)[1] |
---|---|---|
H-1 |
Kapolei, Hawaii (HI-93) to Honolulu, Hawaii (HI-72) Associated route: H-201 |
27.16 |
H-2 |
Pearl City, Hawaii (H-1) to Wahiawa, Hawaii (HI-99) |
8.33 |
H-3 |
Halawa, Hawaii (H-1 & H-201) to Marine Corps Base Hawaii |
15.32 |
The Federal Highway Administration gives money to four routes in Alaska and three routes in Puerto Rico under the same program as the rest of the Interstate Highway System. However, these routes do not have to meet the same standards as the Interstate routes in the main part of the United States.
“ | Highways on the Interstate System in Alaska and Puerto Rico shall be designed in accordance with such geometric and construction standards as are adequate for current and probable future traffic demands and the needs of the locality of the highway.[3] | ” |
Alaska's Interstates do not have signs to mark them, although they all have state highway numbers that are not the same as the Interstate numbers.[4]
Like Alaska, Puerto Rico signs its Interstates as territorial routes, and the numbers are not the same as their official Interstate designations. Many of the territory's routes are freeway-standard toll roads.[5]
Primary Interstate Highways | |
---|---|
Signed | |
Unsigned | |
Lists | |
Major Interstates highlighted |