What caused the housing bubble? Wendell Cox, writing in Joel Kotkin’s New Geography blog, identifies one culprit that most analysts have overlooked: “smart growth” regulations. He points out that there wasn’t a significant housing bubble in about half the country, including some high-growth areas like the Houston, Dallas and Atlanta metro areas. “Where the bubble inflated the most,” he writes, “it was in a metropolitan environment of strong land use controls or artificially constricted land supply (called compact development or smart growth).” Restrictions on development, he explains, inflate the price of existing housing. Environmental restrictions do have their costs.