Yet another study in a long line of others provides evidence that land-use regulations restrict housing supply. A new paper identifies a correlation between land-use regulations in California cities and the growth rate for housing units. Kip Jackson finds that California zoning rules and other land-use restrictions not only reduce the growth rate of new housing stock, but a new regulation can actually be expected to reduce the existing stock of housing by 0.2% per year. This correlation is greatest when looking only at multifamily buildings, where each new restriction results in 6% fewer apartments built annually.

Kip uses panel data on California land-use regulations from 1970-1995. Researchers sent surveys to municipal planning departments to create a dataset including both the regulations in effect in each city and the year they were enacted. The panel dataset allows Kip to use two-way fixed effects. That means that his results control both for factors that affect housing growth in all cities at a given time and for factors that affect growth in a specific city over time.

This survey data makes it possible to study both the effects of the total quantity of rules along with the effects of specific rules. Kip finds that rules that are likely to make it more difficult to build in the future lead to an increase in building permits at the time they are implemented. For example, urban growth boundaries and rules that require a supermajority council vote to approve increased residential density spur current year housing permits. This increase is likely due to developers’ belief that building permits will become more difficult to obtain the longer the new regulation is in effect. He points out that some studies that fail to find a relationship between zoning and housing supply may find this null result because of rules that change the timing of development while reducing it over the long-term. Aggregate indexes of regulation across cities, such as the Wharton Residential Land Use Regulatory Index, can’t measure the changing effect that a rule has over time.

Kip’s approach of using panel data to study the effects of land-use regulations is similar to Ed Glaeser and Bryce Ward’s study of the Boston area. They similarly find that more regulations are associated with reduced residential construction. Unsurprisingly, Glaser and Ward find that this reduced housing supply contributes to higher prices.

This new evidence adds to the extensive body of work demonstrating that land-use regulations reduce the stock of housing relative to what we would see in a free market. It’s particularly important in California, home to some of the country’s most regulated cities and the cities where land-use liberalization could have huge potential benefits in terms of allowing more people to live in high-productivity places.