In Pixar's Cars, Radiator Springs is associated with Route 66.
The film draws heavily on the history and visual character of the real U.S. Route 66, the highway that connected Chicago and Santa Monica after opening in 1926. The fictional town's decline follows the construction of a faster interstate bypass, echoing the effect that modern highways had on many older roadside communities.
Route 66 gives the story a setting connected to American travel, roadside businesses, and changing transportation technology. Sally Carrera explains the town's past to Lightning, helping him see that Radiator Springs is more than an inconvenient stop on his way to a race.
The road is sometimes confused with Interstate 40, which replaced or bypassed portions of Route 66 in the real American Southwest. In the film's fictional geography, Route 66 is the historic road linked to Radiator Springs.