Upzoning in New York City and Philadelphia Associated with Meaningful Increases in Housing Production Activity
May 11, 2026
By Julian Mura-Kröger, NLIHC Research Intern
A recent Urban Institute report by Yipeng Su, Will Curran-Groome, and Yonah Freemark titled “How Big Upzonings Affect Housing Supply,” analyzed the long-term impacts of major zoning reforms on New York City and Philadelphia’s housing supplies. The authors find that upzoned areas, defined primarily as those that saw regulatory changes allowing developers to construct buildings with larger square footage, enabled more housing development activity in both cities, with an additional 4,100 units generated in New York than would have otherwise been built without these zoning changes, and an additional 4,000 housing unit permitted citywide in Philadelphia.
With data from New York City’s PLUTO database and the Philadelphia Department of Licenses and Inspections, the authors identified parcels and “block faces” which had increased zoning capacities after a series of neighborhood-specific rezonings during the de Blasio administration in New York and Philadelphia’s 2012 comprehensive zoning overhaul. They then compared these over several years to areas that had similar pre-zoning reform development patterns, but which were not actually upzoned in order to single out the impacts of upzoning. The reforms in question included a variety of adjustments to the cities’ zoning codes, such as changes to buildings’ maximum heights, setbacks, and buildable areas. Considering that floor area ratio—a measure of the overall density of a building relative to the parcel of land it is on—is one of the most significant influencers of a given development’s number of housing units, the authors relied on this as their primary determinant of whether an area was “upzoned” or not.
In New York City, the authors found positive and statistically significant effects on housing supply following upzoning, with the average upzoned parcel holding roughly 1.1 more units than a non-upzoned parcel four years after these changes. The authors found that 4,100 additional units were built in the seven study neighborhoods due to the zoning changes.
The results varied substantially between neighborhoods, however. For example, Gowanus, a historically industrial neighborhood already undergoing residential transformation, saw the largest increase in housing post-upzoning, while the Jerome Avenue upzoning in the Bronx saw lower housing production rates following its zoning reforms. This highlights the key role of existing market dynamics in shaping the outcomes of upzoning: if zoning regulations are not the limiting factor to housing supply before upzoning, this change will be unlikely to stimulate increases in housing production.
In Philadelphia, upzoned areas saw similar numbers of total permitted housing projects compared to non-upzoned areas, but significantly more permitted housing units per project than their counterparts. These differences were most prominent in 2021 when a ten-year tax abatement period for new construction was ending but became apparent starting six years after the passing of the citywide zoning changes. At this peak, upzoned block faces—what the authors define as sets of properties located next to each other on the same block—attracted 0.17 additional permitted housing units than non-upzoned block faces. This translates to 4,000 additional units per year permitted by the city. Further, upzoned areas in Philadelphia eventually grew to account for 60% of all new housing permitting in the city by 2018, despite only constituting 39.7% of the study area’s land. These patterns followed existing geographic development patterns, with permits concentrated in neighborhoods in and surrounding Center City. This mirrors the findings in New York City, where upzoning could not trigger housing production activity on its own.
The authors also noted that the upzonings may have helped contribute to gentrification and displacement pressures in the areas in which they were focused, naming other studies in New York City which have found that upzonings were associated with different aspects of gentrification, including changes to a neighborhood's racial, income, and education composition. Considering this and the fact that areas in both cities without pre-existing housing demand saw limited or negative housing production following upzoning, the authors emphasize that upzoning cannot be relied upon as a means of distributing the benefits and burdens of housing production across a city equally, even if it is an effective tool for addressing regional housing shortages.
Read the report here.