Where iin the Lower 48 are TC's the most popular, least...?

It's a rare thing to see a truck camper at a state park in Indiana. When we do see one, it really looks odd. I see some in the area where I live and work parked in front of the owners house (well, actually only 1), not on any truck. I see that more in driveways than in any campground.

I would say, a very, very wild estimate, in Indiana where I live, for every 400 travel trailers, motor homes, pop-up campers, and fifth wheels parked at someone house, you'll see 1 truck camper.