Industrial wasteland backdrop
Interesting that for the first half of the film (up until they get to Chicago) every time there's a shot of their car going down the road, nearly all of them show steel mills, factories, etc in the background. There's even the moment where they're driving past one such factory on the highway, and Iris or Molly (I forget which) comments about being thankful she doesn't have to work there.
Sort of gives a view of that working class background, where a lot of people are desperate to avoid the fate of working in a factory or steel mill or whatever. And that was around the time when a lot of the factories were closing down, too, around the time that this part of the country started being referred to as "the rust belt". Surely, it's no accident that the film begins in Akron, Ohio.