Research

Many cities in the US have eliminated minimum parking requirements (MPRs) as part of policy reforms aimed toward increasing housing supply, yet empirical research has primarily focused on the effects on parking instead. I quantify the causal effect of MPRs on housing supply by analyzing two MPR removals in Seattle in 2010 and 2011. Using a heterogeneity-robust difference-in-differences estimator to leverage within-city variation in treatment, I find that eliminating MPRs led to 17 more new multifamily housing units each year, per census block group on average. The MPR removals also operate along the extensive margin, increasing the likelihood of any new multifamily housing unit by 13%. Housing supply effects exhibit nonlinear heterogeneity depending on local transit characteristics and housing costs. Finally, using a permit-level spatial regression discontinuity design specification, I find an average increase of 3.4 more new multifamily housing units per permit.