Nighttime view of Interstate 240 in Asheville

Interstate Guide

Since the early 2000s, Interstate Guide has documented America's Interstate Highway System through photography, route histories, business routes, and reference material. The site covers both the familiar and overlooked parts of the national network.

Browse Interstate highways by route number or state, explore historical features and trivia, follow proposed corridors, and discover the stories behind the roads that connect the country.

Explore Interstate Guide

Browse Interstate routes, discover business loops, explore historical features, and follow the continuing evolution of America's highway network.

✓ Mainline Interstates

✓ Auxiliary Routes

✓ Future Interstates

✓ Former Routes

✓ Unsigned Routes

✓ Business Routes

Browse by Route Number Browse by Route Number Interstate families and branch routes. Browse by State Browse by State Routes organized geographically. Business Routes Business Routes Former alignments and downtown connectors. Features Features History, trivia and numbering guides. Interstate Guide Updates What's New Recent additions and updates. About Interstate Guide About Interstate Guide Contributors and project history.
1974 Interstate System Map
The Interstate System as shown in the 1974 Rand McNally Road Atlas. The Federal Aid Highway Act of 1968 increased the Interstate system by 1,500 miles. The 42,500 mile system then was envisioned for completion in 1980.

The Interstate Highway System has evolved substantially since the early years of completion. Today the system continues to grow with new corridors developed with Congressional authority, such as I-69 between Texas and Indiana, the completion of I-49 in Arkansas and Louisiana and the southern extension of I-27 from Lubbock to Laredo, Texas. Interstate Guide documents both the original network and the routes added through decades of expansion.

Interstate Guide currently documents:

86 Mainline Routes
258 Auxiliary Routes
28 Future Corridors
27 Former Routes
414 Business Loops & Spurs
Illustrated with an archive of 11,729 photographs, historic film scans, and preserved DOT project schematics and interchange concept layouts across all 50 states, DC, and Puerto Rico.
Vintage Chicago Skyway sign Interstate Numbering Guide Numbering guidelines for the Eisenhower Interstate System. Why is there an I-238 but no I-38? Read More →
Future I-49 in southwest Arkansas Proposals and Unbuilt Routes Previously proposed or suggested long distance and regional Interstate corridors that were never realized or otherwise remain unconstructed. Read More →
Interstate Trivia and Records Trivia and Records The shortest, longest, newest, and strangest Interstate highways. Read More →

Recent Updates

Updated photos covering both ends of Interstate 280 in Ohio from July 2024, July 2025 and July 2026.
Route Marker

Interstate 280 Ohio

Updated photos covering both ends of Interstate 280 in Ohio from July 2024, July 2025 and July 2026.

2026-08-20 15:45:04
Updated coverage of both ends of Interstate 475 in Ohio with photos shot on July 22, 2024.
Route Marker

Interstate 475 Ohio

Updated coverage of both ends of Interstate 475 in Ohio with photos shot on July 22, 2024.

2026-08-20 14:57:22
Updated photos of both ends of I-275 in Michigan with photography from July 22, 2024 and July 19, 2026.
Route Marker

Interstate 275 Michigan

Updated photos of both ends of I-275 in Michigan with photography from July 22, 2024 and July 19, 2026.

2026-08-20 12:32:27
Updated coverage at the east end of Interstate 96 in Detroit with photos from 07/22/24 and 07/19/26.
Route Marker

Interstate 96

Updated coverage at the east end of Interstate 96 in Detroit with photos from 07/22/24 and 07/19/26.

2026-08-20 10:06:21

View All Updates →