Facts and figures on the U.S. highway system

by Federal Highway Administration

Longest Interstate Routes Interstate From To Miles I-90 Seattle, WA to Boston, MA 3,020.54 miles I-80 San Francisco, CA to Teaneck, NJ 2,899.54 miles I-40 Barstow, CA to Wilmington, NC 2,555.40 miles I-10 Los Angeles, CA to Jacksonville, FL 2,460.34 miles I-70 Cove Fort, UT to Baltimore, MD 2,153.13 miles Shortest (2-Digit) Interstate Routes Interstate From To Miles I-97 Annapolis to Baltimore, MD 17.62 miles I-99 Bedford to Bald Eagle, PA 53.00 miles* I-73 Emery to Greensboro, NC 56.70 miles I-19 Nogales to Tucson, AZ 63.35 miles I-66 Strasburg, VA to Washington, DC 74.80 miles (* Additional miles of I-73 in NC and I-99 in PA are expected to be built) East-West Transcontinental Routes Interstate From To Miles I-10 Los Angeles, CA to Jacksonville, FL 2,460.34 miles I-80 San Francisco, CA to Teaneck, NJ 2,899.54 miles I-90 Seattle, WA to Boston, MA 3,020.54 miles North-South Transcontinental Routes Interstate From To Miles I-5 San Diego, CA to Blaine, WA 1,381.29 miles I-15 San Diego, CA to Sweetgrass, MT 1,433.52 miles I-35 Laredo, TX to Duluth, MN 1,568.38 miles I-55 New Orleans, LA to Chicago, IL 964.25 miles I-65 Mobile, AL to Gary, IN 887.30 miles I-75 Miami, FL to Sault Ste Marie, MI 1,786.47 miles I-95 Miami, FL to Houlton, ME 1,919.74 miles States with Most Interstate Mileage States Number Miles Texas 17 routes 3,233.45 miles California 25 routes 2,455.74 miles Illinois 23 routes 2,169.53 miles Pennsylvania 22 routes 1,759.34 miles Ohio 21 routes 1,572.35 miles States with Most Interstate Routes States Number Miles New York 1,674.73 miles 29 routes California 2,455.74 miles 25 routes Illinois 2,169.53 miles 23 routes Pennsylvania 1,759.34 miles 22 routes Ohio 1,572.35 miles 21 routes Most Costly Routes (Eligible for Interstate Construction Funds Based on 1991 Cost Estimate) Interstate From To Cost I-95 Miami, FL to Houlton, ME $8.0 billion I-90 Seattle, WA to Boston, MA $7.5 billion I-75 Miami, FL to Sault Ste Marie, MI $5.1 billion I-10 Los Angeles, CA to Jacksonville, FL $5.0 billion Interstate Routes Which Traverse the Most States Interstate States Number I-95 FL, 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-80 CA, 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-10 CA, 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.

Interchanges

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.