In Pixar’s Cars, Interstate 40 bypasses Radiator Springs and contributes to the town’s decline.
The film explains that Radiator Springs once benefited from traffic along Route 66. When Interstate 40 opened nearby, travelers stopped using the old road, leaving the town increasingly isolated. The change explains why its businesses close, its population shrinks, and its surviving residents feel forgotten.
This fictional history reflects a real pattern along U.S. Route 66. Newer highways redirected long-distance traffic away from many older roadside communities, especially after the interstate system expanded in the mid-twentieth century. Cars turns that economic history into the emotional background for McQueen’s stay.
The answer is Interstate 40, not Route 66. Route 66 is the older road associated with Radiator Springs, while Interstate 40 is the newer highway that carries traffic around it. The film uses a fictional town, but its road-history theme is grounded in recognizable American geography.