In Pixar's Cars, Interstate 40 bypasses Radiator Springs and causes the town's decline.
The residents explain that Radiator Springs once benefited from traffic along the old road connecting travelers across the American Southwest. When the newer Interstate 40 was built, motorists no longer passed through the town. Businesses lost customers, and the community became a quiet remnant of an earlier travel era.
This detail provides the social and historical background for the film's setting. Lightning McQueen initially sees the town as an inconvenient stop, but the abandoned highway and local stories reveal what the residents lost. His stay helps bring attention back to the community.
The film draws heavily on real Route 66 landscapes and roadside towns. Route 66 is the older road associated with the town's identity, while Interstate 40 is the bypass that redirects traffic. Mixing up those two roads reverses the story's key historical point.