The original U.S. Route 66 was approximately 2,448 miles long.
That distance described the historic route between Chicago, Illinois, and Santa Monica, California, when Route 66 was part of the national highway system. The road crossed eight states and passed through a changing mixture of cities, farming areas, prairie, mountains, and desert.
The mileage is usually presented as approximately 2,448 miles because Route 66 had multiple realignments over its lifetime. Road builders straightened sections, bypassed town centers, and shifted traffic onto newer alignments, so no single mileage figure describes every period equally.
Modern travelers may cover a different distance depending on which surviving alignments, business loops, city streets, and detours they follow. The traditional published figure remains 2,448 miles, making it a standard fact in histories and guides to the original highway.