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

Finished adding photos of the end points for the planned route of Interstate 343 along the Muskogee Turnpike in eastern Oklahoma. I-343 has nothing to do with I-43, but the Oklahoma Transportation Commission nonetheless approved the numbering for the route in 2025. AASHTO approved the application at the Annual Fall 2025 meeting.
Route Marker

Future Interstate 343 Oklahoma

Finished adding photos of the end points for the planned route of Interstate 343 along the Muskogee Turnpike in eastern Oklahoma. I-343 has nothing to do with I-43, but the Oklahoma Transportation Commission nonetheless approved the numbering for the route in 2025. AASHTO approved the application at the Annual Fall 2025 meeting.

2026-08-14 15:13:37
Created a page for the proposed western branch of Interstate 42 between IH 35 in Noble County, Oklahoma and I-49 in Springdale, Arkansas. ArDOT and ODOT applied for the designation to AASHTO on October 5, 2023. Efforts to designate the U.S. 412 corridor as an Interstate go back to legislation introduced by Senators in both states on May 21, 2021. The 42 numbering is based off dropping the one from 412...
Route Marker

Future Interstate 42 Oklahoma and Arkansas

Created a page for the proposed western branch of Interstate 42 between IH 35 in Noble County, Oklahoma and I-49 in Springdale, Arkansas. ArDOT and ODOT applied for the designation to AASHTO on October 5, 2023. Efforts to designate the U.S. 412 corridor as an Interstate go back to legislation introduced by Senators in both states on May 21, 2021. The 42 numbering is based off dropping the one from 412...

2026-08-14 15:09:26
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.
Route Marker

Future Interstate 644 Oklahoma

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.
Route Marker

Interstate 4

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

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