The purpose of this project is to analyze changes in the location of manufacturing activity in the U.S. between 1963 and 1992 in order to see whether these changes are influenced by differences in environmental regulations among states. The Census Bureau's longitudinal Research Database provides information at five-year intervals for all manufacturing plants. Using these data, each active plant in each period is categorized as opening, closing, expanding, or contracting. These data are aggregated up to the state-level to create dependent variables such as the number of newly opened plants in a state during a five year interval. The explanatory variables for the estimation include regulatory measures such as enforcement activity, pollution abatement expenditures, and state laws, and other factors influencing location such as taxes, wages, and unionization. This research is important because it will develop a new state-level data set on manufacturing activity, and it will help quantify the impact of state imposed environmental regulations on the location of manufacturing activity.