A House Divided? Roll Calls, Polarization, and Policy Differences in the U.S. House, 1877–2011

The study of political conflict in legislatures is fundamental to understanding the nature of governance, but also difficult because of changes in membership and the issues addressed over time. Focusing on the enduring issue of civil rights in the United States since Reconstruction, we show that using current methods and measures to characterize elite ideological disagreements makes it hard to interpret or reconcile the conflicts with historical understandings because of their failure to adequately account for the policies being voted upon and the consequences of the iterative lawmaking process. Incorporating information about the policies being voted upon provides a starkly different portrait of elite conflict—not only are contemporary parties relatively less divided than is commonly thought, but the conflict occurs in a smaller, and more liberal, portion of the policy space. These findings have important implications for a broad range of work that uses elite actions to compare political conflict/polarization across time.