The US EPA’s command-and-control NOx policies of the early 1990s are associated with a 3.1 percentage point reduction in the likelihood of manufacturing plants vertically integrating the electricity generation process. During the same period California adopted a cap-and-trade program for NOx emissions that resulted in no significant impact on distributed electricity generation in manufacturing. These results suggest that traditional command-and-control approaches to air pollution may exacerbate other market failures such as the energy efficiency gap, because distributed generation is generally recognized as a more energy efficient means of producing electricity