The Inexact Science of Congressional Redistricting

Incumbent politicians are understandably nervous when electoral rules are altered. In the case of the U.S. House of Representatives, members are well aware that a change in decade is accompanied by the near certainty that their own district lines will be redrawn. These incumbents know that changes resulting from the reallocation of congressional seats among states and the shift of population within states could have a shattering effect on their careers: their districts could be eliminated; they could be thrown into a district with another House incumbent; their district lines could be radically redrawn, destroying their traditional bases of support.Incumbents' unease is transformed into serious worry by one additional fact:de jurecontrol of redistricting is out of their hands. State legislatures and governors, the Justice Department (for those states falling under the Voting Rights Act) and ultimately the courts determine the fate of incumbents.Of course, the ostensible purpose of congressional redistricting in accordance with the decennial census is to ensure that congressional representation reflects the changes in the geographical distribution of the nation's population and thus to ensure that the members of the House from each state represent approximately the same number of citizens. Putting that principle into practice creates opportunities for the parties to increase their strength in the House but it also causes tremendous uncertainty among incumbents.Looking at political science research on the effects of redistricting on the fortunes of incumbents, one might wonder why they worry. In 1972 I reported findings of my study on incumbents who lost their elections after redistricting.