United States System of Highways Adopted for Uniform Marking by the American Association of State Highway Officials

The ‘Birth Certificate’ of America’s numbered highways, including Route 66.

Prior to 1926, long-distance motoring relied on a chaotic patchwork of named “Auto Trails” sponsored by private booster associations, leading to overlapping, confusing, and often unreliable route markers. Rapid post-WWI automobile adoption and expanding cross-country travel made this lack of centralized coordination unsustainable for both state planners and motorists. To resolve the mess, the federal government and the American Association of State Highway Officials (AASHO) established a joint board in 1925 to design a logical, publicly controlled highway grid. Formally adopted in November 1926, the new system replaced regional named trails with uniform white shields and a nationwide grid, using even numbers for east-west routes and odd numbers for north-south ones. This map was one of the first publicly released to define the newly organized network of interstate highways.

A base map by the United States Geological Survey was overprinted in bright red with the established routes, each accompanied by a number. Iconic highways that would come to define the landscape of American motor tourism include U.S. 66, U.S. 1, U.S. 30, U.S. 40, and U.S. 101. Cities large and small are labeled throughout, highlighting how both urban and rural communities would greatly benefit from the new legislation. Published in 1926 in Washington, D.C., by the Government Printing Office. Originally issued in a report by the Bureau of Public Roads (part of the Department of Agriculture) under Chief Thomas H. MacDonald.