Gerrymandering Roll Calls in Congress, 1879–2000


  • Katz would like to thank the Center on Advanced Study in the Behavioral Sciences for generous support.

Gary W. Cox is professor of political science, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0521 ( Jonathan N. Katz is professor of political science, Division of the Humanities and Social Sciences, California Institute of Technology, D.H.S.S 228–77, Pasadena, CA 91125 (


We argue that the standard toolbox used in electoral studies to assess the bias and responsiveness of electoral systems can also be used to assess the bias and responsiveness of legislative systems. We consider which items in the toolbox are the most appropriate for use in the legislative setting, then apply them to estimate levels of bias in the U.S. House from 1879 to 2000. Our results indicate a systematic bias in favor of the majority party over this period, with the strongest bias arising during the period of “czar rule” (51st–60th Congresses, 1889–1910) and during the post-packing era (87th–106th Congresses, 1961–2000). This finding is consistent with the majority party possessing a significant advantage, either in “buying” vote options, in setting the agenda, or both.