Since the publication of Frederick Jackson Turner's famous essay, historians have implicitly recognized the significance of community characteristics on levels of economic opportunity. Nevertheless, even though the last two decades have witnessed the publication of a number of occupational mobility studies of a wide variety of communities, the nature of the community under examination has been largely overlooked. Thus, while the authors of these studies have frequently found different levels of mobility, the practical necessity of focusing on one community in these undertakings has precluded any systematic attempt either to explain variances among communities or to measure precisely the impact of community characteristics on levels of opportunity.