The housing crunch has been well documented in high-cost big cities, where rents and mortgages break the bank. Now it has moved into the rest of the country.

The culprit is too little housing, and it began two decades ago. In the three years leading up to the Great Recession, homebuilders started about two million homes a year. That number plunged during the crisis and never fully rebounded. Since 2010, builders have started about 1.1 million new homes a year on average — far below the 1.6 million needed to keep up with population growth. America is millions of homes behind, and it gets worse each year.

I spent a week this summer reporting in Kalamazoo, Mich., which isn’t an obvious candidate for a housing crisis. But prices exploded as the supply of homes fell behind the need. Now even middle-class families earning six figures struggle to make ends meet there, and Michigan lawmakers are subsidizing developers who build for those residents. The Times published my article about it this morning.

In today’s newsletter, I’ll explain how this happened nationwide, why it could take a long time to fix and what policymakers are doing about it.

Cities and states understand they have a housing problem. To increase the pace of construction, many have cut back regulatory barriers — like zoning and environmental rules — that make housing slow and expensive to build. Since 2018, for instance, states including California, Oregon, Montana and Arizona have passed laws to allow duplexes and small apartment buildings in neighborhoods that once contained only single-family homes.