From what I've seen, any part of the country where there is a lot of outdoor recreation such as fishing, hunting,
touring & sight seeing, Ocean beach recreation etc. This hints at the south east and west. A lot of travel isn't necessary as there are so many places fairly close together. Thus the mileage stays lower as the clock ticks away.
There are a lot of motivations for owning the RV. Some people use them just to follow NASCAR racing while others just want to go to the woods, mountains, or beach for the weekends within a couple hours of travel.
Some owners do one vacation a year for a week or two to some far off area and the rest of the time it sits beside the house. I see so many like that around where I live. They sit more than they are used.
Another thing that flushes them out is when fuel cost soar. People seem to start dumping them.
But in the south, south east, mid Atlantic, and mid West it seems so many RV's (of any type) get occasional
use each year. and the years roll up faster than the miles. Often an owner passes away unexpectedly and the
widow and her family just want to get rid of it in as condition for whatever they can get for it.