In the 1970s, the New York City Housing Authority helped champion an innovative development in the South Bronx. Using air rights over the Harlem Metro-North rail line, three buildings known as Morrisania Air Rights housing were built on steel-lattice frames over the sunken rail bed. As the number of new residents strains the city's housing stock, Curtis + Ginsberg Architects proposes continuing to build over the remaining seven miles of that same Bronx rail cut. The 60-foot-wide railway is easier to span than the massive layout Hudson Yards is building over, and the prefabricated buildings would absorb the sounds from trains, unlocking the potential for commercial and green spaces on the surrounding underdeveloped land. The 16,000 potential units could house 46,000 residents, and the development would bridge the neighborhoods that have been separated by the train tracks for more than a century.