This article presents a computationally assisted analysis of conceptual changes in American national unity during the nineteenth century through grammatical singularization of the phrase United States in multiple contexts. The study uses corpora ranging from tens of millions to multiple billions of words assembled from books and newspapers published between the late eighteenth and early twentieth centuries. It is among the first of its type to draw on such a variety of broad-based resources. Our findings include significantly slower and less uniform movement toward singular treatment of the nation than has been previously assumed, as well as surprisingly similar rates of change in newspapers and books. We conclude that event-driven historical narratives of national unity centered on the outcome of the Civil War, as well as media-specific claims about the nationally unifying role of print during the period, are not well supported by the data. We consider the implications of performing cultural analysis with large-scale data and suggest an alternative model of conceptual evolution to explain both the observed rate of change and the convergence across media forms.