U.S. Route 66 originally covered 2,448 miles from Chicago, Illinois, to Santa Monica, California.
The highway was established in 1926 as part of the original U.S. Highway System. Its route crossed Illinois, Missouri, Kansas, Oklahoma, Texas, New Mexico, Arizona, and California, linking the Midwest with the Pacific coast.
The mileage was not perfectly fixed throughout Route 66's history. Road realignments, bypasses, and changes to the western terminus altered the measured distance. The commonly cited original length is 2,448 miles.
Route 66 was removed from the U.S. Highway System in 1985, but many surviving alignments and roadside landmarks remain. Modern historic-route maps may show different distances because they include only drivable segments.