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Why the U.S. government built three top-secret cities during WWII

“Secret Cities,” a new exhibition at the National Building Museum, traces the Manhattan Project’s experimental urbanism

In the 1940s, the government built three secret cities from scratch as part of the Manhattan Project. Prefabricated houses, like those by SOM shown above, helped establish a good quality of life.
SOM © Torkel Korling, courtesy Skidmore, Owings & Merrill LLP

Midcentury suburbia is usually viewed through the lens of middle-class idealism: safe neighborhoods with affordable homes for families, picket fences, lawns where kids can play, good schools, and ample room to park your car. They’re the product of gainful employment and tight-knit communities. In the 1940s, the U.S. government built three such cities from scratch and historians today consider them to be among the most successful architecture and urbanism experiments of the 20th century. But these seemingly utopian enclaves have a troubling origin story: the atomic bomb.

The top-secret Manhattan Project—the WWII program that developed the nuclear weapons the United States dropped on Hiroshima and Nagasaki—also gave rise to three top-secret cities: Oak Ridge, Tennessee; Los Alamos, New Mexico; and Hanford, Washington. In the 1940s, these cities—which eventually had a combined population of over 125,000 people—were built from scratch and in total confidentiality.

In “Secret Cities,” a new exhibition at the National Building Museum, senior curator Martin Moeller investigates the design and development of these urban environs and their enduring influence today.

The Manhattan Project was a proving ground for architectural innovations, like prefabrication which was used to build the B-1 “Flat Top” houses in Oak Ridge, Tennessee.
National Archives and Records Administration

“These cities were proving grounds for emerging ideas about town planning, architecture, and construction,” Moeller said during a tour of the exhibition, which is open now until March 3, 2019.

The government prioritized three things in its Manhattan Project cities: security (it was a top-secret military program, after all); efficiency (the cities needed to be built swiftly and meet the bottom line); and livability (since the government needed to recruit top workers, it wanted them to be happy uprooting their lives to live and work in demanding conditions). To pull off this hat trick, the U.S. Army Corps of Engineers, led by Lieutenant General Leslie Groves, hand-picked top architects to conceive the master plans.

The government entrusted Skidmore Owings & Merrill—then a relatively modest architecture firm—to design and plan Oak Ridge, which the Building Museum argues was the most significant secret city design wise.

Faced with pressure to build fast, build well, and build at scale, SOM leaned on prefabrication, the Garden City movement, innovative materials, and modular design. The strategy worked. It took just six months for SOM to construct a town with housing, a city center, and school.

While considered on the bleeding edge at the time, many of the design ideas SOM deployed wouldn’t work today: We know Garden Cities begat suburban sprawl and Cemesto—the lightweight, waterproof, fire-resistant wonder material used in many houses—contained asbestos.

Segregation was also designed into these cities; the living conditions of white, African American, and Latino residents were far from equal. Plus, the government used eminent domain to take the land it wanted to build the cities and there was no community input on how the cities would be developed. However, the cities as an urbanism experiment demonstrate what’s possible when the government decisively tries to create a good quality of life for (most of) its people.

To build the Secret Cities quickly and efficiently, architects experimented with a number of housing types, like this trailer.
Edward Westcott. National Archives and Records Administration

“There were scientists and engineers who were doing this important work, there was an agreement that they needed to feel at home, they need to have a community that felt ‘normal,’” Moeller says. “It was considered important to create housing and environments that were comfortable for the people who would be working there.”

The Secret Cities were definitely military cities. They were fenced off and shrouded in mystery, no one knew exactly what was going on in them, and they didn’t appear on any maps during the war and even after. A USGS map of New Mexico published in 1953—eight years after WWII ended—didn’t include Los Alamos. The highly classified nature of the cities meant that residents couldn’t come and go freely nor speak about their work in public. However—aside from the guard towers and security checkpoints—the towns didn’t feel entirely militaristic.

“During this National Emergency, the government built single family houses in what you could now consider typical suburban neighborhoods instead of jamming these people into dormitories and barracks, as I would think most any other country in the world would have done,” Moeller says. “These cities were conceived as forward looking communities, [the government] really wanted places that were idyllic and were great places to raise families despite the very serious purpose of them.”

The SOM-designed housing in Oak Ridge included single-family prefab homes of different sizes and designs. The B-1, or “Flat Top,” was the most common and included custom-designed plywood furniture. The famous developer William Levitt used some of the same prefab techniques in his Levittown houses.

Some residents lived in trailers, which they spruced up to make more comfortable and homey. After it became clear that single-family homes wouldn’t be able to accommodate the rapidly growing population, SOM designed multi-family apartment buildings.

In some ways, these cities were the ultimate expression of patriotism. Joseph Allen Stein, an architect who worked on prototype housing, commented: “War housing can be an example of our war aims. The new housing can raise the morale of workers and be a constant reminder of the meaning and purpose of democracy.”

As idyllic as the government envisioned its Secret Cities, segregation and racism was still prevalent. African Americans in Oak Ridge were assigned to plywood hutments, which were significantly less comfortable than white residents’ housing.
Edward Westcott. National Archives and Records Administration

The Secret Cities were far from perfect. Because of racial discrimination, African Americans were mostly hired for service work and they, along with some white residents, were assigned to hutments—rudimentary plywood structures with no insulation or indoor plumbing—in a separate part of Oak Ridge, which was more heavily surveilled than the rest of the city.

The residents of the cities were closed off culturally and didn’t have access to the same wealth of leisure activities that the general public did, though the cities did have their own recreation centers and cinemas, and Oak Ridge had its own symphony orchestra. Shopping options were limited, and some goods were scarce just as they were throughout the country due to wartime rationing. In a 1953 New Yorker story, residents lamented only having eight paint choices for their houses.

The Building Museum collected oral histories of life in these cities and it was a mixed bag in terms of how former residents experienced life. Some remarked that it felt like living in a prison while others enjoyed the gated community exclusiveness. (Moeller’s own father-in-law was a nuclear physicist in Oak Ridge and thought life was pleasant there.)

The government owned all of the houses in Oak Ridge, charged the residents low rent, and took care of all maintenance issues. It levied no taxes and handled fees for city services like garbage collection, police, and fire department. The government also provided low-cost or free health care. Oak Ridge also had fantastic schools. But that all came to an end after the war. In The Death and Life of Great American Cities, Jane Jacobs mentioned that Oak Ridge’s demilitarization caused some residents to protest the loss of their services, amenities, and way of life.

Billboards reminded Oak Ridge residents of the confidential nature of their work.
Courtesy of the U.S. Department of Energy and the Oak Ridge Public Library

Building a city from scratch has been an enduring interest of architects. Today, we see that in Sidewalk Labs’ efforts to build a connected neighborhood in Toronto, New York City’s Hudson Yards megaproject, and San Francisco’s embroiled Shipyard. To Moeller, the Secret Cities offer lessons for contemporary architects and it’s all about process.

“The organization, that’s what I keep coming back to,” he says. “What made this work wasn’t just clever design and good engineering...That level of cooperation, the level of collaboration, the innovation in that whole process is what fascinates me.”

The most significant innovation born from the Secret Cities, from an architecture perspective, is the emergence of the architecture-engineering-construction superfirm, which we see today in leading practices. SOM had to adopt a do-it-all approach due to the clandestine nature of the Manhattan Project. After the war, the government continued to work with SOM on large-scale complex projects, which helped position SOM as the post-war era’s dominant architectural practice.

What’s most fascinating to me is how decisively the government worked to get these Secret Cities up and running. The Army Corps of Engineers signed off on the design ideas swiftly and embraced new modes of thought. I wonder what could happen today the government today acted with the same urgency to build more housing, the same dedication to quality of life in cities, and the same consideration for overall well being (segregation aside, of course).

“Secret Cities: The Architecture and Planning of the Manhattan Project” is on view at the National Building Museum until March 2019. Visit for more.