The slums were cleared because they were really awful places. They were threats to the health of those who lived there, and to the viability of the city around them.

Chicago, the city with which I’m most familiar, surveyed every housing unit in the city for Residential Chicago, a report published in 1942. Eight percent either needed major repairs or were unfit for use. Only 85% of dwelling units had private baths.

Slum conditions were concentrated in the oldest areas of the city, the former mansions and townhouses of the South Side that were among the few areas open to Negroes arriving from the South seeking jobs in industrial Northern cities and freedom from Southern oppression. The discrimination in cities like Chicago, Pittsburgh, Philadelphia, or Cleveland was less overt than in the Jim Crow South, but no less pernicious. The Great Northern Migration accelerated during World War II, making overcrowding even worse in the limited housing available to African-Americans. By the early 1950s, the need to improve conditions for those in Chicago’s Bronzeville, Pittsburgh’s Hill District, Harlem, and similar neighborhoods was urgent. The term blight was borrowed from biology, as decay in one part of a city seemed to relentlessly spread to adjacent blocks. What could halt this process?

The prescription written by city planners and housing advocates—clearing entire neighborhoods and starting over—was agreed on by experts of the day, but was one that proved to have unpleasant side effects. Congressional wrangling over cost led to delays and cut-rate solutions. Modernist ideas about street patterns, separation of uses, and architecture ignored important lessons taught by 3000 years of urbanization, although that wasn’t well understood for decades. What might have been an alternative treatment—improving existing buildings and dwelling units—just wasn’t in the tool kit of the era, and was both expensive and impractical in many cases. For every handsome masonry building that could have been rehabbed in these neighborhoods, there were many precarious wooden firetraps lacking structural integrity, adequate exits, insulation, electrical and plumbing lines. Residential buildings were, at the time, largely seen as wasting assets with limited lifespans.

The longing sometimes seen for the tight-knit black communities of the 1940s and 1950s sometimes looks past the segregated society that created those conditions. As segregation eased with the end of racial restrictive covenants, upwardly mobile African-Americans could move to nicer neighborhoods, and the old black neighborhoods were no longer home to all income segments. Once blacks could patronize downtown department stores and big new chain supermarkets, the small clothiers or corner groceries of the historic Negro neighborhoods, often with limited selections and high prices, lost much of their appeal.

Alas, city planning and urban renewal, like most human endeavors, were subject to errors in judgment and unanticipated delays. So construction of replacement dwelling units lagged years, sometimes decades, behind the original plans. Political winds changed, and in many cities deep-seated racial prejudices of city council members limited where new public housing could be built and who qualified to live there. In many cities, the land cleared with the best of intentions for good new housing was still standing vacant, and easy to repurpose, as city leaders in the 1950s sought to build new superhighways, university campuses, and modern industrial districts. Few examples come to mind of “tourist attractions” built on slum clearance land; the clearance around St. Louis’s Gateway Arch project was a large and complex multidecade effort in which tourism played only a small role.