In Pixar's Cars (2006), Interstate 40 is the highway that bypassed Radiator Springs.
The film explains that Radiator Springs prospered when travelers used Route 66, but its economy declined after Interstate 40 diverted traffic away from the town. Lightning McQueen's accidental arrival reveals how much the residents have struggled since the bypass was built.
This detail reflects real changes along U.S. Route 66. Interstate 40 replaced much of the long-distance route's role across the Southwest, leaving some former highway towns with fewer visitors and businesses.
The fictional geography is inspired by real Arizona and California landscapes. U.S. Route 66 is the historic road through Radiator Springs, not the bypass itself, so the two roads should not be confused.