This project examines differences across states in pollution regulation and what impact these differences have had on productivity at existing manufacturing plants and the location of new manufacturing plants. First, different measures of regulation will be compared across states: pollution abatement expenditures, regulatory enforcement activities, state regulatory budgets, and stringency of state environmental laws. Differences in political, demographic, and economic variables across states are used to help explain the differences in regulation. Second, production data for manufacturing plants in selected industries will be taken from the Census Bureau's Longitudinal Research Database to identify differences in productivity levels and growth rates across the plants within each industry. These differences will then be compared with state regulatory intensity measures to see whether high regulation states have plants with lower productivity. Finally, information from the Census of Manufactures on the geographic distribution of new manufacturing plants in the 1070s and 1980s will be examined for evidence that firms respond to differences in pollution regulation when locating new plants.