This op-ed is part of a series on manufactured housing and solutions to help mitigate threats facing mobile home residents. Read our first story on health impacts of private equity ownership.

Punctuating the country is an unknown world of mobile home parks that are often seen but rarely recognized. These communities are everywhere: scattered along highways, in urban crannies in California, Florida, and the Sunbelt, on exurban territory from the Northeast to the Pacific Northwest, next to factories, farmland, mines and military bases. Blink and you’ll miss them. The National Register of Historic Places certainly has.

There is not a single mobile home or mobile home park in the National Register — a glaring omission that, if addressed, challenges the preservation field to join the fight for affordable housing.

Over the last hundred years, mobile homes have housed millions as and where needed. Today, they are home to 21 million people, or about one in every 16 Americans. They are legitimate and permanent parts of the American landscape. Even so, city officials, historians and preservation professionals have largely disregarded mobile homes, and their residents, as aberrations.

Part of the confusion is in the name.

Originally termed “trailers” because they could be attached to a car and hauled away, beginning in the 1950s manufacturers expanded the units and rebranded them as “mobile homes.” In the 1970s, with the introduction of federal construction codes, the industry again rebranded their products to “manufactured housing” — even larger, far less mobile units that are professionally delivered from factory floor to home site. Despite the industry’s preference, for many residents, the term “mobile home” has stuck, and many communities continue to call themselves mobile home parks.

The truth is, mobile homes are not very different from the average suburban home. The vast majority do not move once they are sited, nor do their residents. Some 71% of mobile home residents own their homes, higher than the national homeownership rate for all forms of housing. The biggest difference is their affordability: On average, a new site-built home costs four times as much as a new “manufactured” home.

A possible solution, sidelined

Even amid a housing affordability crisis, mobile homes are seldom seen as a possible solution — with the rare exception of Oakland, California, which recently updated its zoning ordinance to allow mobile homes in all zones that permit residential use. In most cases, planning authorities discriminate against further park development through restrictive zoning laws that relegate communities to peripheral and non-desirable areas, if they are allowed at all. Banishment to concealed pockets where many parks were originally built on unincorporated land and grandfathered, perpetuates false negative stereotypes about mobile home residents.

Put plainly, restrictive zoning is housing discrimination at its most obvious, out in the open. But this discrimination is so blatant, and legally codified, that it is not seen as such. Moreover, restrictive zoning of mobile home parks has artificially constrained the supply of affordable housing, despite high demand. As a result, residents often have nowhere else to go, creating a captive audience ripe for exploitation. Enter private equity.

In recent years, some of the largest private equity firms, including Blackstone, Apollo Global Management, and The Carlyle Group, are making big “recession-proof” bets on mobile home parks. Between 2014 to 2022, investors purchased 800,000 lots, representing nearly 20% of all mobile homes — double the rate of private equity ownership of apartment units.

What is unique to mobile homes is that they are still classified as “chattel,” or moveable personal property — such as a car — rather than real estate. This means that not only do mobile homes decrease in value over time, but that residents, even those who own their home outright, must still pay rent on the land underneath.

By increasing both lending and rental rates, investment firms are squeezing the vulnerable at every turn. As private equity moves in, costs and delayed repairs pile up. Parks purchased by investors have seen rents and fees balloon. Evictions have increased, as has wholesale destruction to make room for redevelopment. The race to the top for the wealthy few is being fueled by squeezing the last wages out of the working poor.

What can be done to protect mobile home parks and their residents?

Several options have had various degrees of success, such as cooperative ownership models and recent moves by legislators to introduce statewide caps on rent increases in mobile home parks. One tool activists have yet to test, however, is historic preservation.

Listing mobile home parks in the National Register would only trigger a review process if federal funds are used in their purchase or redevelopment, meaning that it would not be the best tool to immediately limit rent and fee increases or private equity takeovers. However, historic designation would change peoples’ minds about their critical importance in the modern American housing landscape.

Fighting for an American original

To potentially be listed in the National Register of Historic Places, properties must meet certain criteria, including historic significance to a time at least 50 years in the past. Given their contributions to mid-century American history, the argument for the significance of older mobile home parks is easy to make.

The importance of trailers during World War II cannot be overstated. Many war time factories were built by roving bands of workers who took their trailers with them, with more trailers popping up on nearby fields and once-empty lots when production of war materiel began. The flexibility of trailers to meet the housing needs of workers meant that the United States ramped up manufacturing far faster than would have been possible with only traditional housing options. The trailer is one of the unsung heroes of the home front.

This ability of trailers to quickly mobilize wherever and whenever needed was again on display following the passage of the GI Bill. Look at aerial photos of postwar college campuses; chances are you’ll see rows and rows of trailers nearby, providing on-demand housing to new students and their families.

In the 1950s, following the introduction of larger units with modern conveniences, mobile homes were everywhere, even making their mark on popular culture. Soon, as housing construction began to catch up with demand, and suburban development stretched into once unincorporated land, negative stereotypes, officially expressed by regulations, became undeservedly pervasive. Nonetheless, the presence of mobile homes continued to grow, offering critical housing options for essential workers, young families and older adults with limited incomes.

The preservationist’s catch-22

But historical significance isn’t all that’s necessary to be eligible for the National Register. Properties also need a high degree of integrity, meaning that properties should look and feel like they did during the period of their historical significance. It is much harder to argue for the integrity of mobile homes, because the ability to change over time is one of their defining features.

Aged mobile homes are frequently mended with substitute parts and alterations that do not match their original character. Mobile home scholar Allan D. Wallis coined a term to describe this aesthetic flexibility: design by applique, or the unique patchwork character created by layers of piecemeal modifications. Here, flexibility, rather than a strict adherence to the original, is what gives mobile homes their vernacular integrity.

But flexibility is a catch-22 for preservation practice: To keep what makes mobile homes unique, they must be allowed to change over time. This, by definition, would mean they lose “integrity.”

The preservation field has tied itself into knots.

One way to begin to see a path out of the confusion is by knowing what remains. While a few inventories already exist, such as a Vermont reconnaissance study and a Los Angeles survey, preservation professionals need to document existing conditions further. Another way forward is to build consensus in the field, which is best done through a Preservation Brief that outlines the key elements and history of mobile homes.

Ultimately, what’s needed is for State Historic Preservation Offices, which review nominations to the National Register, to be more lenient in their interpretations, remembering that “it is not necessary for a property to retain all its historic physical features or characteristics” in order to have integrity. Mobile home parks are living, malleable places, and to include them in meaningful numbers in the National Register means moving away from a “culture of preciousness” that puts materials ahead of people.

Seeing mobile homes and mobile home parks as historic is both a preservation and equity issue. Opening the National Register of Historic Places to mobile homes would, finally, recognize them for their undeniable importance to modern America, both in the recent past and today. Such a shift in perception from aberration to recognition would challenge ill-informed notions of their actual mobility that form the premise behind restrictive zoning laws that limit new, affordable manufactured housing communities where they are needed most.

By challenging undignified prejudices, beginning with its own, the preservation field can be at the forefront of the fight for affordable housing. The preservation field can, and should, be open to change.

This post was originally published on Next City.