When Congress approved the Federal-Aid Highway Act of 1956, it authorized what was then the largest public works program in U.S. history. The law promised to construct 41,000 miles of an ambitious interstate highway system that would crisscross the nation, dramatically expanding America's roadways and connecting 42 state capital cities and 90 percent of all American cities with populations over 50,000. Its goal was to eliminate unsafe roads, inefficient routes and traffic jams that impede fast and safe cross-country travel. President Dwight Eisenhower called the massive infrastructure project “essential to the national interest.”

But the highway expansion, implemented largely between the late 1950s and the early 1970s, came at a huge cost to America’s urban communities of color.

According to estimates from the U.S. Department of Transportation, more than 475,000 households and more than a million people were displaced nationwide because of the federal roadway construction. Hulking highways cut through neighborhoods darkened and disrupted the pedestrian landscape, worsened air quality and torpedoed property values. Communities lost churches, green space and whole swaths of homes. They also lost small businesses that provided jobs and kept money circulating locally—crucial middle-class footholds in areas already struggling from racist zoning policies, disinvestment and white flight.

The neighborhoods destroyed and families uprooted by highway projects were largely Black and poor, wrote New York University law professor Deborah N. Archer in her article “White Men’s Roads Through Black Men’s Homes: Advancing Racial Equity Through Highway Reconstruction.” And that was by design, she noted. Policymakers and planners saw highway construction as a convenient way to raze neighborhoods considered undesirable or blighted. And they deployed the massive infrastructure elements—multi-lane roadbeds, concrete walls, ramps and overpasses—as tools of segregation, physical buffers to isolate communities of color.

Hardly a major city with a significant minority population went unscathed by the legislation: New York, Miami, Chicago, Minneapolis, Pittsburgh, Oakland, Nashville, Baltimore, Atlanta—and more. “By the time the interstate highway system was completed...” Archer wrote, “it had fundamentally restructured urban America.”

One of the most influential post-World War II urban planners was New York City’s “construction coordinator” Robert Moses, who oversaw all public works projects in the nation’s largest metropolis, including an astonishing array of its roadways, bridges, tunnels, housing projects and parks. Not only was Moses arguably the most powerful unelected official in the state’s history, but his influence on federal highway policy extended well beyond New York. He was a leading proponent of the idea that the best way to eradicate the supposed slums where Black people lived was to build highways through them.

“Our categorical imperative is action to clear the slums,” Moses said in a 1959 speech. “We can’t let minorities dictate that this century-old chore will be put off another generation or finally abandoned.” Moses, who was also the chairman of the New York City Slum Clearance Committee, said that the highway construction must “go right through cities and not around them.” Two of the city’s main arteries he created, the Cross-Bronx and Brooklyn-Queens Expressways, did just that, cutting through the heart of the Bronx and Red Hook neighborhoods.

The 1956 federal highway act ran with this strategy, offering to paying 90 percent of the cost of states’ new roadways—with the caveat that they consent to build them through every major city to connect the emerging suburbs to downtown centers where commuters worked and shopped. According to Archer, highway engineers came to think of “killing two birds with one stone” to “improve traffic conditions and remove undesirable populations.

In the first half of the 20th century, Miami’s culturally vibrant Black community of Overtown was widely considered the “Harlem of the South” and “Little Broadway.” But after the passage of the 1956 highway bill, the expansion of I-95 through Miami led to the destruction of 87 acres of housing and commercial property in the community. According to Richard Rothstein’s The Color of Law: A Forgotten History of How Our Government Segregated America, only 8,000 of an estimated population of 40,000 remained in Overtown after the highway expansion. Blocked from moving into white neighborhoods, displaced residents were forced to crowd into nearby sections of the city already struggling with poverty and urban decay.

Cities around the country experienced similar devastation. Shortly after the highway bill, the construction of a vast roadway system cut through the Black neighborhood of Rondo in St. Paul, Minnesota, a mixed-class community known for its thriving cultural life, social clubs and integrated schools. Despite neighborhood resistance, an estimated 600 families lost their homes, and 300 businesses were shuttered when I-94 divided the community.

“It wasn’t just physical—it ripped a culture, it ripped who we were,” Minnesota governor Tim Walz later commented. “It was an indiscriminate act that said this community doesn’t matter...this convenient place to put a highway so we can cross over this place and go from the city out to the suburbs.”

At the time the highways were being built, the civil rights movement was gaining momentum. Congress and federal courts began to outlaw racist housing tactics such as restrictive housing covenants that prevented Black residents from buying into white neighborhoods and “redlining," a longstanding governmental zoning practice that had denied federally insured home loans to anyone living in a designated Black community.

As anxiety rose about the prospect of integrated neighborhoods, highway construction offered a solution: substantial physical barriers that could be used to reinforce racially determined neighborhood boundaries. The federal government often predicated highway funding on a state or city’s promise to use it for that purpose.

“Instead of going through Black communities, some interstate highways encircled them in an attempt to contain and confine black residents and skirt constitutional prohibitions on racial zoning,” wrote Archer. “In this way, the highway system was a tool of segregationist agenda, becoming ‘a protective maze of freeways, moats, concrete parapets and asphalt no man’s lands’ that separated white communities from Black communities and protected white people from Black migration.”

In Atlanta, according to Princeton University historian Kevin Kruse, I-20 was designed to serve as a boundary between the Black and white communities. “By razing impoverished areas downtown and segregating the races in the western section, Atlanta leaders hoped to keep downtown and its surroundings a desirable locale for middle-class whites,” wrote Kruse in The New York Times in 2019. But, he added, the “so-called urban renewals and the new Interstates only helped speed white flight from the city.” According to Kruse, roughly 60,000 whites left Atlanta for the suburbs in the 1960s and another 100,000 in the 1970s.

I-81 was built through the heart of Syracuse, New York to destroy the 15th Ward, a Black community that city planners believed was too close to the city’s jewels—Syracuse University and the downtown. “[I-81] decimated a close-knit African American community,” wrote Alana Samuels for _The Atlantic. “_And when the displaced residents from the 15th Ward moved to other neighborhoods, the white residents fled.”

Moving, she wrote, had just gotten a whole lot easier: “There was a beautiful new highway that helped their escape.”