Interstate Highway System Trivia

Updated August 5, 2020 | Infoplease Staff

Facts and figures on the U.S. highway system

by Federal Highway Administration
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See also: The Story of the U.S. Interstate

Longest Interstate Routes

InterstateFrom ToMiles
I-90 Seattle, WA to Boston, MA 3,020.54 miles
I-80San Francisco, CA to Teaneck, NJ2,899.54 miles
I-40 Barstow, CA to Wilmington, NC 2,555.40 miles
I-10Los Angeles, CA to Jacksonville, FL2,460.34 miles
I-70Cove Fort, UT to Baltimore, MD 2,153.13 miles

Shortest (2-Digit) Interstate Routes

InterstateFrom ToMiles
I-97Annapolis to Baltimore, MD17.62 miles
I-99Bedford to Bald Eagle, PA53.00 miles*
I-73Emery to Greensboro, NC56.70 miles
I-19Nogales to Tucson, AZ63.35 miles
I-66Strasburg, VA to Washington, DC74.80 miles
(* Additional miles of I-73 in NC and I-99 in PA are expected to be built)

East-West Transcontinental Routes

InterstateFrom ToMiles
I-10 Los Angeles, CA to Jacksonville, FL2,460.34 miles
I-80San Francisco, CA to Teaneck, NJ2,899.54 miles
I-90Seattle, WA to Boston, MA3,020.54 miles

North-South Transcontinental Routes

InterstateFrom ToMiles
I-5San Diego, CA to Blaine, WA1,381.29 miles
I-15San Diego, CA to Sweetgrass, MT1,433.52 miles
I-35Laredo, TX to Duluth, MN1,568.38 miles
I-55New Orleans, LA to Chicago, IL964.25 miles
I-65Mobile, AL to Gary, IN887.30 miles
I-75Miami, FL to Sault Ste Marie, MI1,786.47 miles
I-95Miami, FL to Houlton, ME1,919.74 miles

States with Most Interstate Mileage

States NumberMiles
Texas17 routes3,233.45 miles
California25 routes2,455.74 miles
Illinois23 routes 2,169.53 miles
Pennsylvania22 routes1,759.34 miles
Ohio21 routes 1,572.35 miles

States with Most Interstate Routes

States NumberMiles
New York 1,674.73 miles29 routes
California2,455.74 miles25 routes
Illinois 2,169.53 miles 23 routes
Pennsylvania 1,759.34 miles 22 routes
Ohio 1,572.35 miles21 routes

Most Costly Routes (Eligible for Interstate Construction Funds Based on 1991 Cost Estimate)

Interstate From ToCost
I-95Miami, FL to Houlton, ME$8.0 billion
I-90Seattle, WA to Boston, MA$7.5 billion
I-75Miami, FL to Sault Ste Marie, MI$5.1 billion
I-10Los Angeles, CA to Jacksonville, FL$5.0 billion

Interstate Routes Which Traverse the Most States

I-95FL, GA, SC, NC, VA, DC, MD, DE, PA, NJ, NY, CT, RI, MA, NH, ME 16 States
I-90 WA, ID, MT, WY, SD, MN, WI, IL, IN, OH, PA, NY, MA 13 States
I-80CA, NV, UT, WY, NE, IA, IL, IN, OH, PA, NJ 11 States
I-70 UT, CO, KS, MO, IL, IN, OH, WV, PA, MD 10 States
I-10CA, AZ, NM, TX, LA, MS, AL, FL 8 States

State Capitals

All but five State capitals are directly served by the Interstate System. Those not directly served are:

Juneau, AK
Dover, DE
Jefferson City, MO
Carson City, NV
Pierre, SD

Oldest Segments

The oldest Interstate segments actually predate the establishment of the Interstate system. Early examples include a portion of the Grand Central Parkway in Queens, New York, which was opened to traffic in July 1936 and later was incorporated into the Interstate System as I-278. The Pennsylvania Turnpike between Irwin (southeast of Pittsburgh) and Carlisle (west of Harrisburg) was officially opened in October 1940 and is now designated as I-76 and I-70. Other freeways and toll roads were incorporated into the System rather than build new competing Interstate routes.

Rest Areas

An exact count of rest areas on the Interstate System is not available. However, a count in 1972 reported 1,214 rest areas in existence. The number still operational today is not expected to differ dramatically from the 1972 figure.


An exact count of the number of interchanges on the Interstate System is not available. However, a 1978 count found 14,231 interchanges. This number has likely increased somewhat over the intervening years.

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