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
Interstate families and branch routes.
Browse by State
Routes organized geographically.
Business Routes
Former alignments and downtown connectors.
Features
History, trivia and numbering guides.
What's New
Recent additions and updates.
About Interstate Guide
Contributors and project history.
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:
Interstate Numbering Guide
Numbering guidelines for the Eisenhower Interstate System. Why is there an I-238 but no I-38? Read More →
Proposals and Unbuilt Routes
Previously proposed or suggested long distance and regional Interstate corridors that were never realized or otherwise remain unconstructed. Read More →
Recent Updates
Interstate 644 is the proposed renumbering for the tolled Creek Turnpike around the south and east sides of Tulsa, Oklahoma. The designation was approved by AASHTO at the Fall 2025 meeting of the Route Numbering Committee. Included in this new page are photos covering both ends from 07/11 and 07/12/26.
2026-08-12 17:28:57
Updated coverage of the west end of Interstate 4 in Tampa with photos taken along both directions of I-275 both today and earlier this year. Ongoing construction to Spring 2027 addresses traffic congestion at the Downtown Interchange where the two routes meet.
2026-08-12 16:48:07
Fired up the scanner and added two maps showing the proposed alignment of Interstate 178 into Allentown, Pennsylvania.
2026-08-11 16:06:47
Updated coverage of both ends with photos from July 25, 2024. Added a scanned map from 1975.
2026-08-11 12:03:54