Planning Magazine

How the National Zoning Atlas Visualizes and Demystifies the Power of Zoning

Sara Bronin’s sweeping vision gives planners a tool to push for reform.

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Bronin created the atlas “to help people break through the jargon” of zoning codes. Photo courtesy of Sara Bronin.

"Zoning has so many different impacts on the way that we live," says Sara C. Bronin, founder and director of the National Zoning Atlas.

At a time when zoning is a popular topic among planners and nonplanners alike, everyone from policymakers to average citizens is hungry for data on land use. Launched in 2023, the National Zoning Atlas serves up that information in a layperson-friendly interface. With the goal of democratizing, demystifying, and digitizing the country's more than 30,000 zoning codes, the Atlas is helping communities from Connecticut to Montana visualize land use policies and put data behind their housing reform efforts.

"We hope that the National Zoning Atlas becomes a tool to help people break through the jargon, so they don't have to read a 300-page zoning code or look at a color-coded zoning map to understand the power that zoning has on our communities," Bronin says.

On an episode of the People Behind the Plans podcast, Bronin joined APA Editor in Chief Meghan Stromberg to discuss the role the National Zoning Atlas is playing in zoning reform efforts around the country and the potential for this data to influence policy changes that impact everything from climate to transit to equity.

This interview has been edited for length and clarity, but you can listen to the whole conversation at or wherever you get your podcasts.

STROMBERG: Tell us a bit about your background and where your interest in the built environment came from.

BRONIN: I grew up in Houston, which many people say is the largest city in the country without zoning. It does have zoning-like rules, to be clear, but it developed in a way that is sprawling, somewhat incoherent, and in many places not too beautiful. Going to architecture school and then law school really encouraged me to interrogate our built environment, and when you start unraveling that thread, all layers of inquiry lead right back to zoning.

STROMBERG: The National Zoning Atlas has its roots in a state-level initiative called Desegregate Connecticut. Tell us a bit about this organization and how it inspired a national mapping effort.

BRONIN: The efforts in Connecticut were motivated by land use professionals questioning their role in creating entrenched segregation in our state. If you look at Connecticut cities and towns, income-based and even race- and ethnicity-based segregation is pretty clear, but nobody had done a survey across the state to enable an apples-to-apples comparison of all the zoning codes.

"In Connecticut, we were able to use summary statistics to catalyze conversations at the state legislature to start the process of updating state zoning laws."

Looking back on that atlas, I was surprised to find that 91 percent of the state land allowed single-family housing as a right, and just two percent of land allowed housing for three or more families as a right. Those two data points alone painted a powerful story about how local rules added up to something that was hurting our economy, our environmental sustainability, and of course equity.

We created the methods that are now used in the National Zoning Atlas in Connecticut to address those issues. The Connecticut Zoning Atlas enabled people to see how zoning worked in their towns and calculate the percentage of land that was zoned for single-family housing versus multifamily housing. And that's exactly what you see in the National Zoning Atlas today.

STROMBERG: How can planners use the state atlases to push for state housing reform?

BRONIN: In creating statewide atlases, we found that you can use the summaries of the state in ways that are extremely influential on policy. In Connecticut, when we completed the atlas, we were able to use those summary statistics to catalyze conversations at the state legislature to start the process of updating state zoning laws, including laws on accessory dwelling units and minimum parking requirements.

We also know that the Atlas has been used at the local level by planners in city planning documents, regional analyses, local reforms, and policy analyses. We hope that when planners use the tool, they are delving into all of its features, including minimum lot size, minimum parking requirements, and requirements that housing developments must be connected to transit to inform their decisions.

STROMBERG: One state that has already seen some outcomes from its zoning reform effort is Montana. Tell us what's going on there and how they used a zoning atlas to facilitate reform.

BRONIN: They call it the "Montana miracle" — and I know it's been covered in Planning and The New York Times — because of the suite of zoning reforms that were made at the state level. The nonpartisan Frontier Institute, which led those conversations, played a big role in developing an atlas for the state's largest cities that informed the debate. Their CEO, Kendall Cotton, cites the Montana Zoning Atlas when talking about the ability to bring legislators and city leaders the facts about how their communities zone. The ability to compare one city to the next, he says, has been instrumental in making change and informing the public about their current zoning and the opportunities to change in the future.

STROMBERG: Where do you see the National Zoning Atlas going next?

BRONIN: We're already seeing collaborative research projects on a few different big-picture topics where zoning has played or could play a role. One example of that is the relationship between zoning and sea level rise. We are working in collaboration with the Regional Plan Association and others to develop an understanding of where in the New York City metro area we are putting housing and correlating that with areas where that housing is likely to flood.

Our geospatial coordinator, Scott Markley, has been generating ideas for additional research. One is zoning in urban heat clusters; another is exploring the relationship between zoning, transportation, and carbon emissions. Zoning has so many different impacts on the way that we live that the possibilities for overlaying our data with other datasets are many. I look forward to all of that going forward.

Sophia Burns is APA's content associate.