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Interstate Highway System Fascinating Facts

Interstate By the Numbers

Official Name: Dwight D. Eisenhower National System of Interstate and Defense Highways

Total Miles: 46,837 (2004)

Longest Interstate Routes:
I-90, Seattle, Washington to Boston, Massachusetts, 3,020.54 miles
I-80, San Francisco, California to Teaneck, New Jersey, 2,899.54 miles
I-40, Barstow, California to Wilmington, North Carolina, 2,555.40 miles
I-10, Los Angeles, California to Jacksonville, Florida, 2,460.34 miles
I-70, Cove Fort, Utah to Baltimore, Maryland, 2,153.13 miles

Shortest Two-Digit Interstate Routes:
I-73, Emery to Greensboro, North Carolina, 12.27 miles
I-97, Annapolis to Baltimore, Maryland, 17.62 miles
I-99, Bedford to Bald Eagle, Pennsylvania, 53.00
I-19, Nogales to Tucson, Arizona, 63.35 miles
I-66, Strasburg, Virginia to Washington, D.C., 74.80 miles

Shortest Three-Digit Interstate Routes:
I-878, 0.70 miles, New York
I-395, 0.72 miles, Maryland
I-980, 0.80 miles, California
I-315, 0.82 miles, Montana
I-110, 0.94 miles, Texas

North-South Transcontinental Routes:
I-5 San Diego, California to Blaine, Washington, 1,381.29 miles
I-15, San Diego, California to Sweetgrass, Montana, 1,433.52 miles
I-35 Laredo, Texas to Duluth, Minnesota, 1,568.38 miles
I-55, New Orleans, Louisiana to Chicago, Illinois, 964.25 miles
I-65, Mobile, Alabama to Gary, Indiana, 887.30 miles
I-75, Miami, Florida to Sault Ste. Marie, Michigan, 1,786.47 miles
I-95, Miami, Florida to Houlton, Maine, 1,919.74 miles

States with Most Interstate Miles:
Texas, 17 routes, totaling 3,233.45 miles
California, 25 routes, totaling 2,455.74 miles
Illinois, 23 routes, totaling 2,169.53 miles
Pennsylvania, 22 routes, totaling 1,759.34 miles
New York, 29 routes, totaling 1,674.73 miles

States with Most Interstate Routes:
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

Routes Traversing the Most States:
I-95, 16 states (including Washington D.C.): Florida, Georgia, South Carolina, North Carolina, Virginia, Washington D.C., Maryland, Delaware, Pennsylvania, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire, and Maine

I-90, 13 states: Washington, Idaho, Montana, Wyoming, South Dakota, Minnesota, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, New York, and Massachusetts

I-80, 11 states: California, Nevada, Utah, Wyoming, Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania, and New Jersey

I-70, 10 states: Utah, Colorado, Kansas, Missouri, Illinois, Indiana, Ohio, West Virginia, Pennsylvania, and Maryland

I-10, eight states: California, Arizona, New Mexico, Texas, Louisiana, Mississippi, Alabama, and Florida

All but five state capitals are directly served by the Interstate System. Those that aren’t are Juneau, Alaska; Dover, Delaware; Jefferson City, Missouri; Carson City, Nevada; and Pierre, South Dakota.

Oldest Segments: A portion of the Grand Central Parkway in Queens, New York, opened in 1936 and was later incorporated into the Interstate System as I-278; The Pennsylvania Turnpike between Irwin southwest of Pittsburgh and Carlisle west of Harrisburg opened in October, 1940, and is now I-76 and I-70.

Interchanges: 14,750 (approximate)

Bridges: 55,512 (as of December 2004)

Tunnels: 82 (104 bores)

Highest Elevation: Eisenhower Memorial Tunnel, Clear Creek/Summit counties, Colorado 11,012 feet (east) and 11,158 (west)

Lowest Elevation: Interstate 8, El Centro, California, 52 feet below sea level

Also of Interest: The FHWA's description of how the Interstate Highway System compares to Great Pyramid of Cheops in Egypt and the Great Wall of China.

Source: Federal Highway Administration, Program Administration

Special thanks to Richard Weingroff and Bing Wong

U.S. Census Bureau