Local governments often try to combat housing costs and create affordable housing by passing legislation that changes current zoning and land-use regulations. But the changes are not without controversy. SciLine interviewed Jessica Trounstine, the centennial chair and professor of political science at Vanderbilt University, who discussed why rising housing prices and shortages are happening at the same time, how some zoning policies still lead to segregation, and why many zoning changes that are environmentally friendly are unpopular with the public.

The Conversation has collaborated with SciLine to bring you highlights from the discussion, which have been edited for brevity and clarity.

What’s causing the current housing shortages and high housing costs in the U.S.?

Jessica Trounstine: Most metropolitan areas have seen housing shortages and skyrocketing prices over the last decade, both for rentals and for mortgages. And as those prices have gone up, tax assessments have also gone up, leading to higher property tax bills. So the total amount of money that residents are paying for their housing is higher than it used to be.

When households pay more than 30% of their income toward housing, the census calls those households “cost burdened.” And according to some recent data, more than a third of households in the U.S. are cost burdened, and the figures are even higher for renters than for owners. In some metropolitan areas, greater than 50% of renters are cost burdened.

How do local governments influence housing availability?

Jessica Trounstine: Local governments can make it difficult to build housing, which contributes in a fundamental way to housing shortages and skyrocketing prices. They do things like charge high fees for development or put in place cumbersome review processes. They can implement historical overlays or create open-space requirements.

But the most important way local governments affect housing shortages is by prohibiting density and allowing only single-family, detached units to be built. Many cities explicitly prohibit multifamily housing. Anything from duplexes to high-rises might be prohibited by a city’s zoning or regulatory code.

They can also do things like have requirements for large setbacks from the street. They can enact minimum lot sizes for every unit. Because higher density and smaller housing units are less expensive, these regulations that limit density are correlated with higher housing costs.

Many local land-use regulations have been in effect for a long time. Why are they causing such problems now?

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