List of Interstates - Definition

Primary interstates are the major interstate highways of the United States and are assigned a one or two-digit route number. Even route numbers are assigned to east/west routes, with the lower numbered routes being further south (I-10) and higher numbered routes in the north (I-90). Similarly, odd route numbers are assigned to north/south routes, with the lower numbered routes being further west (I-5) and the higher numbered routes being further east (I-95).

Three-digit interstates are spur or loop interstates that usually service large cities and suburbs. The last two digits of a three-digit interstate are always the number of the parent route, the primary interstate where it originated. If the first digit is odd, the interstate is typically a spur route while if the first digit is even, the interstate is typically a loop route. Three-digit interstates are covered in their parent route's article, and those that have their own articles are linked below. (In the table below, interstates designated with an asterisk are "secret" interstates -- that is, they are not signposted as interstates.)

• Notable exceptions to these numbering standards are Interstate 238 in California and Interstate 99 in Pennsylvania.

Primary Interstates

Interstate 4	- Tampa, FL (I-275) to Daytona Beach, FL (I-95)
Interstate 5	- San Ysidro, CA (Mexican border) to Blaine, WA (Canadian border) Associated routes: I-105 | I-205 | I-305* | I-405 | I-505 | I-605 | I-705 | I-805
Interstate 8	- San Diego, CA to Casa Grande, AZ (I-10)
Interstate 10	- Santa Monica, CA to Jacksonville, FL (I-95) Associated routes: I-110 | I-210 | I-310 | I-410 | I-510 | I-610 | I-710 | I-910
Interstate 12	- Baton Rouge, LA (I-10) to Alton, LA (I-10)
Interstate 15	- San Diego, CA (CA-15) to Sweetgrass, MT (Canadian border) Associated routes: I-115 | I-215 | I-315*
Interstate 16	- Macon, GA (I-75) to Savannah, GA Associated route: I-516
Interstate 17	- Phoenix, AZ (I-10) to Flagstaff, AZ (I-40)
Interstate 19	- Nogales, AZ (Mexican border) to Tucson, AZ (I-10)
Interstate 20	- Kent, TX (I-10) to Florence, SC (I-95) Associated routes: I-220 | I-520 | I-820
I022.png Image:I022.png Interstate 22	- Memphis, TN (I-55 & I-40) to Birmingham, AL (I-20, I-59 & I-65) Under construction - opening 2006
Interstate 24	- Pulley's Mill, IL (I-57) to Chattanooga, TN (I-75) Associated route: I-124
Interstate 25	- Las Cruces, NM (I-10) to Buffalo, WY (I-90) Associated route: I-225
Interstate 26	- Colonial Heights, TN (I-81) to Charleston, SC (US-17) Associated routes: I-126 | I-526
Interstate 27	- Lubbock, TX to Amarillo, TX (I-40)
Interstate 29	- Kansas City, MO (I-35 & I-70) to Pembina, ND (Canadian border) Associated routes: I-129 | I-229
Interstate 30	- Fort Worth, TX (I-20) to Little Rock, AR (I-40) Associated routes: I-430 | I-530 | I-630
Interstate 35	- Laredo, TX (Mexican border) to Duluth, MN (MN-61) Associated routes: I-135 | I-235 | I-335 | I-435 | I-535 | I-635
Interstate 37	- Corpus Christi, TX (US-181) to San Antonio, TX (I-35)
Interstate 39	- Normal, IL (I-55) to Wausau, WI
Interstate 40	- Barstow, CA (I-15) to Wilmington, NC (NC-132) Associated routes: I-140 | I-240 | I-440 | I-540 | I-840
Interstate 43	- Beloit, WI (I-39, I-90 and I-94) to Green Bay, WI (US-41)
Interstate 44	- Wichita Falls, TX (US-287) to St. Louis, MO (I-55) Associated routes: I-244 | I-444*
Interstate 45	- Galveston, TX (TX-124) to Dallas, TX (I-30) Associated route: I-345*
Interstate 49	- Lafayette, LA (I-10) to Shreveport, LA (I-20)
Interstate 55	- La Place, LA (I-10) to Chicago, IL (US-41) Associated routes: I-155 | I-255
Interstate 57	- Miner, MO (I-55) to Chicago, IL (I-94)
Interstate 59	- Alton, LA (I-10 & I-12) to Lookout Mountain, GA (I-24) Associated routes: I-359 | I-459 | I-759
Interstate 64	- St. Louis, MO (I-270) to Chesapeake, VA (I-264 & I-664) Associated routes: I-164 | I-264 | I-464 | I-564 | I-664
Interstate 65	- Mobile, AL (I-10) to Gary, IN (I-90) Associated routes: I-165 | I-465 | I-565 | I-865
Interstate 66	- Middletown, VA (I-81) to Washington, D.C. (US-29)
Interstate 68	- Morgantown, WV (I-79) to Hancock, MD (I-70)
Interstate 69	- Indianapolis, IN (I-465) to Port Huron, MI (Canadian border) Associated route: I-469
Interstate 70	- Cove Fort, UT (I-15) to Baltimore, MD (I-695) Associated routes: I-170 | I-270 | I-370 | I-470 | I-670
Interstate 71	- Louisville, KY (I-64) to Cleveland, OH (I-90) Associated routes: I-271 | I-471
Interstate 72	- Hannibal, MO (US-61) to Champaign, IL (I-57) Associated route: I-172
Interstate 73	- Candor, NC (US-220) to Greensboro, NC (I-40 & I-85)
Interstate 74	- Bettendorf, IA (I-80) to Cincinnati, OH (I-75) Associated route: I-474
Interstate 75	- Ft. Lauderdale, FL (FL-826) to Sault Ste. Marie, MI (Canadian border) Associated routes: I-175 | I-275 | I-375 | I-475 | I-575 | I-675
Interstate 76	- West - Denver, CO (I-70) to Big Spring, NE (I-80)
Interstate 76	- East - Westfield Center, OH (I-71) to Camden, NJ (I-295) Associated routes: I-176 | I-276 | I-376 | I-476 | I-676
Interstate 77	- Columbia, SC (I-26) to Cleveland, OH (I-90) Associated route: I-277
Interstate 78	- Bordnersville, PA (I-81) to New York City, NY Associated routes: I-278 | I-478* | I-678 | I-878*
Interstate 79	- Charleston, WV (I-77) to Erie, PA (PA-5) Associated routes: I-279 | I-579
Interstate 80	- San Francisco, CA (US-101) to Fort Lee, NJ (I-95) Associated routes: I-180 | I-280 | I-380 | I-480 | I-580 | I-680 | I-780 | I-880 | I-980
Interstate 81	- Dandridge, TN (I-40) to Fisher's Landing, NY (Canadian border) Associated routes: I-181 | I-381 | I-481 | I-581
Interstate 82	- Ellensburg, WA (I-90) to Hermiston, OR (I-84) Associated route: I-182
Interstate 83	- Baltimore, MD to Harrisburg, PA (I-81) Associated route: I-283
Interstate 84	- West - Portland, OR (I-5) to Echo, UT (I-80)
Interstate 84	- East - Scranton, PA (I-81) to Sturbridge, MA (I-90) Associated routes: I-384 | I-684
Interstate 85	- Montgomery, AL (I-65) to Petersburg, VA (I-95) Associated routes: I-185 | I-285 | I-385 | I-485 | I-585 | I-985
Interstate 86	- West - Heyburn, ID (I-84) to Pocatello, ID (I-15)
Interstate 86	- East - Erie, PA (I-90) to Elmira, NY (NY-17)
Interstate 87	- New York, NY (I-278) to Champlain, NY (Canadian border) Associated routes: I-287 | I-587 | I-787
Interstate 88	- West - Moline, IL (I-80) to Chicago, IL (I-290)
Interstate 88	- East - Binghamton, NY (I-81) to Schenectady, NY (I-90)
Interstate 89	- Concord, NH (I-93) to Highgate Springs, VT (Canadian border) Associated route: I-189
Interstate 90	- Seattle, WA to Boston, MA Associated routes: I-190 | I-290 | I-390 | I-490 | I-590 | I-690 | I-790 | I-890 | I-990
Interstate 91	- New Haven, CT (I-95) to Derby Line, VT (Canadian border) Associated routes: I-291 | I-391 | I-691
Interstate 93	- Canton, MA (I-95) to St. Johnsbury, VT (I-91) Associated routes: I-293 | I-393
Interstate 94	- Billings, MT (I-90) to Port Huron, MI (Canadian border) Associated routes: I-194 | I-294 | I-394 | I-494 | I-694 | I-794 | I-894
Interstate 95	- Miami, FL (US-1) to Houlton, ME (Canadian border) Associated routes: I-195 | I-295 | I-395 | I-495 | I-595 | I-695 | I-795 | I-895
Interstate 96	- Muskegon, MI (US-31) to Detroit, MI (I-75) Associated routes: I-196 | I-296* | I-496 | I-696
Interstate 97	- Annapolis, MD (US-50) to Baltimore, MD (I-695)
Interstate 99	- Bedford, PA (I-76) to Bald Eagle, PA (US-220)
Interstate 238	- Hayward, CA (I-580) to San Lorenzo, CA (I-880)

Hawaiian Interstates

The interstate highways in Hawaii are signed with the standard Interstate shield, with the letter "H-" prefixed before the number. They are fully controlled-access routes built to the same standards as the mainland Interstate routes.

• Interstate H-1
  Associated route: H-201