Detroit once had 1.85 million inhabitants. Now it has fewer than 740,000. Cleveland and St. Louis, too, are half the size they were in 1950. Across the Atlantic, Liverpool and Leipzig are also dramatically smaller. When so many cities are booming, why are some trapped in decline?
Cities naturally rise and fall as technologies change. Detroit and the other cities of the Great Lakes established themselves as agricultural transport hubs before the Civil War. Afterward, they enjoyed a second growth spurt when American industry settled along waterways for easy access to raw materials such as iron ore. But their geographical advantages eroded over the course of the 20th century as the real cost of moving a ton a mile by rail dropped by more than 90 percent. Manufacturers relocated to lower-wage areas such as the South.