“Where urban highway construction did occur, in urban design terms, it was highly detrimental to the urban fabric; creating physical and psychological rifts that are extremely difficult to bridge and introducing a substantial source of noise and air pollution,” Shelton and Gann wrote. “Cities across the country continue to struggle with this legacy.”

As some of the highways reach the end of their useful life, cities and counties are debating the idea of tearing down urban freeways and replacing them with boulevards, streets, and new neighborhoods. Though it might sound like a headache, tearing down freeways in city centers can reduce air pollution and create parks and public spaces that bring cities together, according to Shelton.

“The removal of urban interstates is a growing trend in the U.S.,” Shelton and Gann wrote. This trend, if carried to its logical extreme, can yield sites of intervention that hold the promise of remaking the American city.”

In Birmingham, for example planners want to see sections of I-20/59 replaced (though the state’s Dept of Transportation has different ideas). Many people in Buffalo, NY want to see the city’s Skyway torn down, and the Austin, Texas, city government has supported a resolution to submerge parts of I-35 and reconnect portions of city. Other urban highways potentially on the chopping block: the Aetna Viaduct in Hartford, Connecticut; Route 29 in Trenton, New Jersey; and Nashville’s downtown loop.

Some cities have already completed freeway teardowns. Boston, for instance, got rid of sections of I-93 as part of the Big Dig, putting parts of the freeway underground and creating more than 45 parks and public plazas. Voters rejected a plan to tear down the Embarcadero Freeway in San Francisco in 1986, but then the Loma Prieta earthquake damaged the highway, leading to its teardown anyway, a construction project that made the San Francisco waterfront more pedestrian-friendly. Milwaukee demolished the Park East freeway in 1999 and urban development has blossomed in the neighborhoods created by the highway’s removal. Manpower Corporation moved its headquarters to the area, and the average assessed land value there grew 45 percent.

It’s an important lesson for some of the nation’s most economically depressed cities, which are considering urban freeway removal projects as a means of economic development. New Haven, for instance, is in the midst of a project called Downtown Crossing, which has removed parts of Route 34 and is putting up new buildings in an area of town bisected by the freeway. The photos below show models of what the area looks like now, and what it will look like when the project is completed.

When the city put in Route 34 in the 1950s, it relocated 881 households and 350 businesses. It’s now hoping to bring businesses and residents back to the area. Already, the city is erecting a 425,000 square foot lab and office building, and Alexion Pharmaceuticals is in the process of building its new headquarters in the middle of this space, which will bring 1,000 jobs to the area.