Recent years have witnessed a dramatic rise in the nationalization of U.S. congressional elections. The correlation between presidential and congressional voting is at levels not seen since the party ballot was in use during the nineteenth century. In this chapter, we evaluate the potential causes of the increased nationalization and examine the consequences of this change for representation in Congress. Based on an analysis of data from 1980–2016, we find that the recent surge in nationalization is most consistent with changes in elite behavior. One major consequence of this change is that legislators are working harder to win elections and maintain control of the chamber, but their efforts have reduced the governing capacity of the institution and severed important aspects of the representative-constituency linkage.