About Interstate Guide

Interstate Guide began in the early 2000s as an effort to document the endpoints of every Interstate Highway with photographs and field observations. It grew alongside other road enthusiast websites devoted to state highway endpoints and historic highway documentation, eventually expanding into a comprehensive guide covering the Interstate Highway System's history, numbering conventions, business routes, and future corridors.

Interstate Guide remains a volunteer effort made possible through the contributions of photographers, researchers, and road enthusiasts from across the United States.

View the complete list of contributors.

Sources and methodology

A variety of sources were used for researching the history, progression and ongoing expansion of the Interstate Highway System. These include newspapers, departments of transportation (DOT) documents and project web sites, contributions and research from site contributors, personal observation from the webmasters, and spatial data from various DOT Geographic Information Systems.

Pages are organized first with an example of a shield photo (when available). Mileage statistics are derived from the Federal Highway Administration (FHWA) Route Log and Interstate Finder, or from state DOT websites or GIS systems. A general overview and history on the route follows, based upon research and field observations.

Some Interstates coincide with High Priority Corridors, and most replaced or paralleled existing U.S. Highways. Ongoing expansion of the system is covered through DOT project websites. Major projects, such as upgrades of outdated interchanges, or completion of missing moves, are also covered with research from road enthusiasts on social media, DOT websites and other online sources.

The aim of the endpoint media is to cover each angle of an Interstate Highway end. That is, the ending of the route, from advance signage to the last exit or freeway end, to the end shield or at-grade intersection where the route concludes. Then routes that tie into or intersect the end of the route are covered from the first advance sign. Additionally the first reassurance marker may be included, showing the beginning of a route.