Environmental regulation of industrial pollution is often incomplete; regulations apply to only a subset of facilities contributing to a pollution problem. Policymakers are increasingly concerned about the emissions leakage that may occur if unregulated production can be easily substituted for...

For political and practical reasons, environmental regulations sometimes treat point-source polluters, such as power plants, differently from mobile-source polluters, such as vehicles. This paper measures the extent of this regulatory asymmetry in the case of nitrogen oxides (NO_x), the most...