the Chicago-Los Angeles route to US 62 or splitting US 60 into multiple branches. The issue was resolved when Oklahoma highway engineer John M. Page identified 66 as an unassigned number, which Avery accepted as the designation for the route.

Although the route was designated in 1926 and signed in 1927, it remained partly unpaved for several years. By 1938, US 66 became the first U.S. highway to be fully paved, improving long-distance travel across the central and southwestern United