The environmental regulations US firms are exposed to are often place-based, incentivizing firms to move to less regulated counties or states. Consistent with this argument, multiplant firms partially regulated under the ozone regulations of the US Clean Air Act offset regulation-induced...

This article proposes and evaluates four hypotheses about US pollution and environmental policy over the last half century. First, air and water pollution have declined substantially, although greenhouse gas emissions have not. Second, environmental policy explains a large share of these trends....