OK, here is the first, very rough, draft of the itinerary for The Great American Drive-in Theater Road Trip. No, it's not an April Fool's joke. That's where the theaters are in the places I haven't gotten to yet. There are a couple of repeats. The Park theater, seen in the strongly backlit picture in the KS presentation, was torn down, but has been rebuilt near Billings, Montana. There are also sections of states already visited where there are more theaters, like southern Idaho, Northern Montana, and southern Ohio.
The trip will head first for Indiana, across southern Illinois to Missouri, then follow the southern loop out to San Diego. Next, up the west coast , then zigzag across the center of the country. That will be more than enough all at once. I'll wait until late summer or early fall to add the far southeastern loop.
On another note, my online resources are failing to get any data on surviving theaters in Canada. The survival rate up north is even lower, but I think there are still some theaters at least in Ontario and Quebec provinces. Anyone have more on that?