Someone needs to plug that spacetime vortex that's stuck on top of 1980s California. Somewhere off screen is Kirk, Spock, Marty McFly, and everyone else who's ever set foot in a time machine.
Sadly, almost every movie is set where the writer(s) are familiar with the area, which is mostly Los Angeles or New York.
Their vast knowledge of the midwest gets us crap like "Jericho," where you can see the Rocky's from Kansas, and in a nearly flat state, you can have only "one bridge into town."
I'm sure this will come as a shock but ... it's cheaper to film closer to your base of operations, where all of your infrastructure and support personnel are already in place. It takes a little bit more than a guy with a camera, some lights, and a folding table with snack foods to film a network series or feature film.
Anyway, The Day After it isn't. More like recent-season 24 meets Threads.
@Daddy: I think taxes are a bigger factor. That's why so much filming takes place in Vancouver and on that desert soundstage (I think in Arizona?) where they filmed that awful Tim Allen biker comedy.