Rick Pildes and Ned Foley have recently posted about making districts more competitive in the next round of redistricting. Competition is plainly an appealing value. As Philip Edward Jones has shown, voters are better informed when races are more competitive, and incumbents are more accountable for their records (good or bad). A large number of competitive seats also leads to a high level of responsiveness for a district map—that is, parties’ seat shares changing briskly as their vote shares shift from one election to another.
However, it’s important not to conflate competitiveness with another critical value: the partisan fairness of district maps. Maps can be highly competitive but still severely skewed in one or another party’s favor (if that party consistently wins most of the competitive races). Maps can also be highly uncompetitive but entirely fair in how they treat the parties (if each party reliably wins an appropriate share of seats). And these aren’t just theoretical points: Eric McGhee and I found that, over five decades of state legislative redistricting, the partisan fairness of district maps was entirely unrelated to their competitiveness. As you can see in the chart below, there’s no link whatsoever between the absolute value of maps’ efficiency gaps (a measure of partisan fairness) and candidates’ average margin of victory (a measure of competitiveness).
Of course, the lack of a connection between competitiveness and partisan fairness doesn’t mean that line-drawers shouldn’t pursue greater competitiveness. It just means that they shouldn’t expect greater competitiveness to yield greater partisan fairness. If we want fair maps, we have to focus on fairness itself—not poor proxies for it.