U.S. Route 66 was established in 1926 as part of the original United States Numbered Highway System.
The highway system was created to give major roads consistent numbers and signs across the country. Route 66 was approved on November 11, 1926, connecting Chicago with Los Angeles before its western terminus was later moved to Santa Monica.
Route 66 was not built entirely from scratch. It combined sections of existing local, state, and auto-trail roads. Oklahoma businessman Cyrus Avery strongly promoted the Chicago-to-California route and became known as a key founder of Route 66.
A common mix-up is confusing the route's establishment with the date its signs first appeared. Route 66 was established in 1926, while signage was erected during the following year. Its 2026 centennial marks a century since the highway entered the national system.