To better understand zoning, we need better data. The zoning data we do have are so sporadic and incomparable between jurisdictions that it’s difficult to assess the effect of zoning laws.

Efforts to create national data on land-use practices and how they change over time have advanced (see the Urban Institute’s National Longitudinal Land Use Survey or the Terner Center’s California land-use survey data).

But investigation and discussion is lacking around what level of government (e.g., counties, towns, townships, or cities) holds the authority to zone what land. No federal entity oversees or stores any data on who zones what land, and discussions that touch on this topic are only beginning to emerge in the public view.

We need a better picture of who zones where

Differentiating who zones where illuminates what sources of data can be used to examine the effects of zoning.

For example, we shouldn’t be gathering data on statutory mentions of zoning or aggregating effects at the county level if all zoning occurs at a municipal level in that state. We should be collecting data from the municipality. Similarly, we shouldn’t use data from counties that only govern unincorporated areas if we are trying to understand certain zoning laws’ effects on dense housing production.

In the process of constructing the first national longitudinal survey of the land-use regulatory practices in jurisdictions in the 50 largest US metropolitan areas, I had to map out what levels of government oversee zoning and land use. This varies widely across states and even within states.

Most cities and villages zone their own land, but similarities across states end there.

The map’s blue scale shows variation in counties’ zoning authority extent. Counties’ zoning authority ranges from full zoning authority over all land (dark blue), to zoning only unincorporated land (medium blue), to only rarely possessing any zoning authority over any unincorporated land (light blue). Zoning and development permitting authority for unincorporated land in those light blue states rests with the state.

Meanwhile, the map’s gray scale shows zoning authority variation in county subdivisions, commonly known as towns or townships. Their authority extent ranges from full zoning authority over all land in New England (dark gray), to zoning just unincorporated areas (medium gray), to only occasionally possessing zoning authority over unincorporated areas (light gray). States in blue don’t have these intermediate-level jurisdiction types.

As affordable housing continues to be a central national concern and as bipartisan support for federal involvement in local zoning swells, we would do well to make sure our policy recommendations are tailored to the local legal realities.

This means beginning with a basic sense of what level of governments needs to work on their zoning ordinances. One size will certainly not fit all when talking about necessary or praiseworthy zoning policies, and research and policy recommendations should reflect that.