Several important studies of institutions assume that the quality of institutions is persistent following some formative historic event. The assumption of institutional persistence, however, begs the question of how these institutions persisted. To better understand this issue, this paper examines the evolution of state courts in the United States. We begin by reviewing the evidence that France, Spain, and Mexico operated civil-law legal systems in territory that would later make up thirteen states. One important philosophical difference between civil-law and common-law legal systems arises from differences in their beliefs regarding the appropriate degree of judicial independence. To show how these beliefs, if persistent, would manifest themselves, we present a model in which legislatures allocate budgets to their judges. In the model, common and civil-law legislatures have different preferences regarding the level of judicial independence. Our model predicts civil-law legislatures will give fewer discretionary resources to their judges when judicial elections are replaced by a system of appointments. We confirm this prediction using state-level data for the period 1961-1999. Finally, we argue that one important reason why civil-law preferences for a weak judiciary appear to have persisted in the American states is that the political culture within state legislatures is slow-moving.