Local governments regulate land use by chopping cities into zones, specifying what can be built in each area. This serves some valuable purposes, like separating homes from heavy industry. But mostly , it serves to protect homeowners. In many cities, including Minneapolis, more than half of the city’s land is reserved for single-family homes.

People should be free to live in a prairie-style house on a quarter-acre lot in the middle of Minneapolis, so long as they can afford the land and taxes. But zoning subsidizes that extravagance by prohibiting better, more concentrated use of the land. It allows people to own homes they could not afford if the same land could be used for an apartment building. It is a huge entitlement program for the benefit of the most entitled residents.

The loose fabric of single-family neighborhoods drives up the cost of housing by limiting the supply of available units. It contributes to climate change, by necessitating sprawl and long commutes. It constrains the economic potential of cities by limiting growth.

In December, the Minneapolis City Council voted 12 to 1 to allow construction of at least three residential units per lot throughout the city as part of a larger package of changes intended to increase housing construction. Under the plan, most construction still will be concentrated in the center of the city and along transit corridors. But the elimination of single-family zoning was crucial in building political support for the plan, ending a system under which more than 60 percent of Minneapolis was sheltered from change.

“Cities are in constant evolution, and we’ve limited that evolution by mandating that two-thirds of the city is exclusively single-family,” said Jacob Frey, the mayor, who made affordable housing the key issue in his 2017 election campaign. Mr. Frey, who is 37, said residents — particularly younger residents — want to live in a different kind of city than did their parents: dense, diverse, vibrant. “And in order to achieve affordability and a diversity of housing options,” he said, “you first have to allow for it.”