Interstate 40 causes Radiator Springs to lose passing traffic in Pixar's Cars.
The film explains that Radiator Springs once benefited from travelers using Route 66. When Interstate 40 opened nearby, most motorists bypassed the old road, leaving the town and its businesses economically isolated.
This fictional history reflects a real pattern along U.S. Route 66. Newer, faster highways redirected long-distance traffic away from many older roadside communities, contributing to the decline of towns that had depended on motorists for fuel, food, lodging, and repairs.
The film uses the highway change as more than background. McQueen's arrival gives Radiator Springs a chance to be noticed again, and the restored road and renewed visitors symbolize the town's recovery. Interstate 40 is therefore a key setting detail and a historical reference point.