
At the beginning of the 20th century, there were virtually no zoning laws in the United States. By 1921, zoning had come to 48 large U.S. cities, representing a fifth of the country's population. By 1932, 1,165 municipal governments had adopted zoning, covering more than two-thirds of the urban population. By 1968, nearly every metropolitan government had zoning, as did large swaths of rural America.
It was a revolution, and a rapid one. Property owners were once allowed to use their land for the most profitable or desirable use: live on it, sell it to a commercial or industrial business, sell it to a developer. Now nearly every municipality has rules that dictate how a piece of land can be used and what kinds of housing, if any, are allowed on it.