Partisan and Incumbency Effects of 1970s Congressional Redistricting

The authors review earlier tests and purpose several new tests of two rival hypotheses concerning the drawing of lines for congressional districts: (1) districting is partisan in nature and favors the candidates (including incumbents) of one party over those of the other, and (2) districting is bipartisan in nature and will equally favor incumbents of both parties. Analyzing data from the 1970s congressional redistricting leads us to reject both hypotheses (with only a handful of states as possible exceptions). Instead, the authors conclude that on balance congressional redistricting in the 1970s preserved the status quo; that is, neither party gained at expense of the other, and incumbents did not benefit at the expense of challengers, with the qualification that incumbents were not forced to run against each other, The haves kept what they had; they did not, by and large, do better. The paper also seeks to explain why minimal change is the most common redistricting pattern.