Detroit was never a beautiful city, but it had a muscular grandeur—broad boulevards radiating from its riverfront core, stolid stone-faced office towers crowding its downtown streets. The mammoth auto factories—including the innovative 1903 Packard plant by Albert Kahn, with its huge spans of column-free spaces—anchored more distant neighborhoods, surrounded by neat grids of wood-frame bungalows. Elsewhere there was street after street of more houses—many large and handsome, nestled under leafy canopies of trees. With so many streets of houses—cut through by wide avenues lined with mom-and-pop stores and small machine shops—the city seemed to go on forever toward the horizon: a vast, flat metropolis, 139 square miles of forever.

In the 1950s, Detroit was the fifth-most-populous city in America, with almost 2 million people, riding a decades-long surge of prosperity. Its wealth supported elegant downtown stores and white-starched restaurants, a first-rate symphony, and an exceptional art museum. Underpinning all the manufacturing and money was an industrious, up-by-the-bootstraps culture, buoyed up by waves of immigrants—Poles, Greeks, Germans, Irish, Mexicans, poor whites from Appalachia, African-Americans from the deep South—who kept remaking the neighborhoods with their own ingredients to create a vibrant urban stew. “The black middle class was born in Detroit in the ’50s,” said Maurice Cox, the city’s visionary new planning director. “It was the locus of the American dream.”