Despite the increased interest among local governments in collecting data on performance measurement, empirical evidence is still limited regarding the extent to which these data are utilized to assess the impact on efficiency of economies of scale and uncontrollable factors. Data envelopment analysis (DEA) is a linear programming method designed to estimate the relative efficiency of decision-making units. In addition to assessing relative efficiency, DEA can estimate scale efficiency and incorporate the impact of uncontrollable factors. Using data from the International City/County Association (ICMA), this study utilized DEA to evaluate the impact of economies of scale and uncontrollable factors on the relative efficiency of municipal service delivery in the United States. The findings from this doctoral dissertation show that uncontrollable variables such as population density, unemployment, and household income suppress the relative efficiency of local governments. Moreover, the findings imply that the prevalence of economies of scale in city governments depends on the types of services these governments provide.