Interstate Highway System Trivia

Updated August 5, 2020 | Infoplease Staff

Facts and figures on the U.S. highway system

by Federal Highway Administration

External Links

Eisenhower Interstate System
Dept of Transportation
Public Roads Magazine

See also: The Story of the U.S. Interstate

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.

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