Roughly 20 million Americans live in mobile homes, once billed as low-cost living. But mobile home parks have become a target investment for real estate companies who are jacking up fees.

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About 20 million Americans live in manufactured or mobile homes. Some own the structures. Most rent the property underneath. And for many, rents are rising. Here’s Anna Casey of Illinois Public Media.

ANNA CASEY, BYLINE: Terry Baker has lived at Wilson’s mobile home park in Urbana, Ill., for more than 20 years. Baker is a retired home health worker and a proud grandmother who was looking for a place of her own after her divorce.

TERRY BAKER: I could not get over the rent. When I moved in here, my rent was $142 a month. Where else was I going to live for that kind of money?

CASEY: Baker’s rent has doubled now. It started to rise three years ago. She describes a letter that residents got.

BAKER: Dear Wilson’s resident, Dennis and I are writing to inform you we have made a difficult decision to sell Wilson’s on University.

CASEY: The local owners sold the community to Colorado-based RV Horizons. It owns mobile home parks in more than 25 states. Its business model is to buy up mom and pop parks and raise the rent. Frank Ralph works at RV Horizons and something called Mobile Home University, a so-called investors’ boot camp that teaches people how to buy mobile home parks. This is from a promotional video on their website.

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FRANK ROLFE: You only rent the land when you own a mobile home park. And the customers are relatively easy to please. They’re just happy to have a roof over their head.

CASEY: The investor who bought the park where Baker lives and 12 others in the county has steadily increased rent and fees. Frank Rolfe wouldn’t return a request for an interview, but in this video from 2015, he laid out his business strategy.

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ROLFE: Yeah. Well, raising the rent is simply part of the Day One purchase because often, the mom and pop has not raised the rent in years. So they’re far below market.

CASEY: It’s unclear how many mobile home parks remain family-owned, but they’re an increasingly popular investment. Just five of the biggest mobile home real estate companies now own nearly 300,000 sites. The largest is Michigan-based Sun Communities. Russell Watson is with the Federation of Manufactured Home Owners of Florida. He liked living in a Sun Community.

RUSSELL WATSON: These guys keep the parks as parks. They aren’t looking to simply displace you and send you on your way.

CASEY: In larger cities, mobile home communities are increasingly redeveloped as more profitable real estate. But Watson, who moved to a mom and pop park in Fort Pierce, says the downside is rents become less affordable when corporate owners take over.

WATSON: And they will rapidly price out people who came to those parks because it was affordable housing.

CASEY: Back in Illinois, residents like Terry Baker are worried that more rent hikes are coming.

BAKER: And if I wanted to move this place, it’s going to cost me $5,000 to $7,000 to move it and set it back up. OK? And they own almost every park around here. They got me by the butt.

CASEY: That’s why Baker and some other Illinois residents are advocating for rent-control measures. But there’s a ban on rent control in Illinois and at least 20 other states. Mobile home owners worried about escalating rents fueled by speculators are pushing for legislation to control them. For NPR News, I’m Anna Casey in Urbana, Ill.

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