In Pixar's Cars, what highway causes Radiator Springs to lose most of its traffic?

In Pixar's Cars, Interstate 40 causes Radiator Springs to lose most of its traffic.

The town once benefited from travelers using Route 66, but a newer interstate bypasses Radiator Springs. With motorists no longer passing through town, local businesses decline and the community becomes isolated from the main flow of traffic.

This detail reflects a real historical pattern along U.S. Route 66. Interstate 40 replaced or bypassed long stretches of the older highway in the American Southwest, including areas associated with the route through Arizona and New Mexico. Cars turns that transportation change into the central economic problem facing Radiator Springs.

Route 66 is therefore not the highway that takes traffic away; it is the historic road where the town is located. Interstate 40 is the newer route responsible for the bypass. The distinction is important because the film's setting is built around the contrast between old roadside travel and modern interstate travel.