Reapportionment and partisan competition: When does reapportionment matter?

This research considers the effects of reapportionment on partisan competition. More precisely, this study develops a set of specifications under which we might expect varying effects of reapportionment on electoral patterns. By considering the history of political competition in the state, the geographic distribution of partisans, the history and methods of previous apportionments, and the political nature of the reapportionment, a set of specific hypotheses regarding the effects can be deduced. The theory is tested by application of it to the state of Oklahoma. Utilizing an interrupted time-series analysis of election results, we conclude that the 1964 reapportionment in Oklahoma had immediate electoral consequences. The 1971 reapportionment had virtually no effect. These findings are consistent with the expectations based on the theory developed in the paper.