The original Route 66 crossed eight U.S. states.
From east to west, they were Illinois, Missouri, Kansas, Oklahoma, Texas, New Mexico, Arizona, and California. The route’s passage through these states helped make it a compact cross-section of the United States, linking industrial cities, farming communities, Great Plains towns, desert settlements, and Pacific-coast suburbs.
Kansas had the shortest section of Route 66, covering only about 13 miles. Despite its brevity, the state still formed one of the eight official states on the route.
Some descriptions mention more places because Route 66 had many alignments, loops, and connections within metropolitan areas. Those local variations do not change the official state count. The route’s overall corridor remained an eight-state journey from Chicago to Santa Monica until its decommissioning.