Baltimore Ecosystem Study Institute of Ecosystem Studies

2011 BES Annual Meeting Presentation and Poster Abstracts

The Effect of Rural Downzoning on Residential Development in Baltimore County
Newburn, David
Co-Authors: Jeff Ferris

Zoning regulations, typically implemented as minimum lot sizes, are one of the primary land-use policies used to reduce farmland conversion. In this study, we use a spatially explicit panel data set of parcel subdivisions spanning from 1967-2007 in Baltimore County, Maryland. The purpose is to analyze the effect of the rural downzoning policy adopted in 1976 on the rate of subdivision development and density. We implement a two-stage difference-in-difference (DID) econometric model of residential development. The first stage analyzes the rate of development, while the second stage analyzes the subdivision density (or average lot size). Explanatory variables for both model stages include parcel attributes within a geographic information system (GIS) on zoning designation, accessibility to employment centers and major roads, land quality, surrounding land uses, and other attributes. This econometric model is able to exploit the subdivision data spanning periods before and after policy adoption in 1976 to identify the heterogeneous spatial treatment effect from rural downzoning. Specifically, our DID formulation includes treatment areas (RC2 and RC4 zoning) and control areas (RC5 zoning) during both the pre-zoning period in 1967-1976 and the post-zoning period in 1977-2007. Our results suggest that rural downzoning in Baltimore County significantly reduced the density of development, but it had minimal effect on the probability of development. Hence, rural downzoning has created overall lower density development, but the rate of development was unchanged after downzoning. In particular, there was a shift of development from major subdivisions into minor subdivisions in the RC2 zoning area.