In Pixar's Cars, Route 66 brings tourists to Radiator Springs before the interstate bypass.
Route 66 is the historic U.S. highway associated with Radiator Springs and the town's former prosperity. The film presents the town as a roadside community whose businesses depended on travelers stopping for fuel, food, and lodging before a newer interstate diverted traffic away.
That premise draws on the real history of U.S. Route 66, which connected Chicago and Santa Monica and became a major symbol of American road travel. The route was removed from the United States Highway System in 1985, although many surviving sections remain historic attractions.
Route 40 and Route 101 are real American highways, but they are not the road central to Radiator Springs' identity. Route 66 is also called the “Mother Road,” a name popularized by John Steinbeck's The Grapes of Wrath.