There are tons of them but it's hard to find the good, safe ones. Some are trailer parks with an "RV Areas". Some are campgrounds that allow extended stays. A lot of these can be sketchy. NC and SC are abundant for these type parks as they offer steady revenue streams for the property owners. Many have traveling contractors (good people) while others have "on our last thin dime" blue tarps on the roof campers. Others are full blown RV Resorts with all amenities and mostly like minded and like condition, newer RV's (people that have the money to comfortably be there). Narrow down the area you desire and start the search...Google Aerial Views are worth every effort. Here's a good link to get you started:
https://www.goodsam.com/campgrounds-rv-parks/snowbird/