On a warm Saturday evening in June 1943, crowds were relaxing on Belle Isle, a retreat slightly larger than New York’s Central Park nestled in the Detroit River, which separates Canada and the United States. Belle Isle’s landscapes and structures were a showcase of great American architecture: Frederick Law Olmsted, Albert Kahn, and Cass Gilbert all were represented. Its botanical garden, yacht club, memorial fountain, golf course, and opulent marble lighthouse offered a serene testament to the grandeur of Detroit.

Exactly what started the riots that night, we’ll never know for sure. There seems to have been a confrontation between a white sailor’s girlfriend and a black man, which led to a brawl. As contradictory rumors raced through the city, the conflagration spread. By the time federal forces intervened to impose law and order three days later, dozens of people had been killed, mostly blacks, and millions of dollars of property destroyed, mostly in the poor, black, inner-city neighborhood of Paradise Valley.

Detroit’s fall can be traced to the race riots of 1943, though many decades of prosperity and achievement still lay ahead. The rise and fall of Detroit is history on an epic scale: Favored by fortune at first, then plowed under its wheel, the city has had a lot of bad luck. But as Oscar Wilde lamented as he languished in Reading Gaol near the end of his life: “I must say to myself that I ruined myself, and that nobody great or small can be ruined except by his own hand . . . Terrible as was what the world did to me, what I did to myself was far more terrible still.”

Houston had suffered race riots, too, during World War I, but fortune would smile on it for most of the 20th century. And when oil prices collapsed in the mid-1980s, sending the city into a depression, it bounced back as if suspended from a bungee cord — even though the oil bust lasted nearly two decades. What Houston did for itself is not merely a model for any city facing the danger of sudden economic decline: The policies that Houston and Texas have followed are proof of concept for the conservative vision of government, which is, essentially, to keep the government off the people’s backs and let a free society find its own way to prosperity.

Detroit, conversely, is proof of concept for the liberal vision of government, which seeks to solve every problem through government, to shape economic development through government, to redress grievances through government, to attain social justice through government, and, finally, to insinuate government into every aspect of our lives. The problems Detroit faced in the latter half of the 20th century would have been enormously challenging no matter what policies it embraced. But it embraced the worst ones and so plunged recklessly down the slope of decline.

Each city has offered a nearly pure exposition of a particular philosophy of government and a vivid demonstration of the results. In the degree of collusion between business and government, in the power of labor unions, in the method of economic development, in the burden of taxation and regulation, in the tolerance for diversity — in all these ways and more, the two cities stand as diametric opposites in the choices a society can make.

By 1943, it was clear that both Detroit and Houston were having a great war. Detroit’s massive car factories had all been converted to war production, and it was churning out tanks, jeeps, and bombers at a dizzying pace. The demand for wartime labor drew more than 300,000 migrants to Detroit, mostly from Appalachia and the South. In 1943, the population was approaching 2 million, and it seemed to be growing with no end in sight. But the race riots had revealed a sore festering beneath the surface, and there were others.