New Analysis Shows Gerrymandering Gives Republicans a Large Advantage in U.S. House

Most of us remember the 2010 elections as when Republicans won control of the U.S. House. A new analysis from the Brennan Center suggests that year's state-level elections had even longer-lasting electoral effects on Congress, helping Republicans to cement their House majority for the remainder of the decade. 

Republicans racked up victories in state legislative and governor’s seats, especially in states where these elected officials control the redistricting process, guaranteeing Republicans greater control over the 2011 redistricting process in these states. The Brennan Center’s analysis seems to suggest this control paid off.

In particular, the authors looked at the twenty-six states that have at least six congressional districts (comprising 85% of Congressional seats) and estimated Republicans enjoy a 16-17 seat advantage in those states as a result of gerrymandered maps drawn by legislatures under Republican control.

A Handful of State Legislatures To Blame

Examining data from the previous three election cycles through several quantitative metrics used to estimate partisan advantage in election results, the Brennan Center concluded that:

- Only seven states account for almost all of the bias in the nation’s congressional maps. MichiganNorth Carolina, and Pennsylvania consistently have the most distorted electoral maps, collectively accounting for an extra 7-10 Republican seats in each of the previous three election cycles. Partisan bias within FloridaOhioTexas, and Virginia jointly accounts for most of the remaining Republican advantage.

- Those seven state maps showing high partisan bias were all drawn by legislatures under single-party control, suggesting a relationship between single-party redistricting and biased maps. Further, the presence of biased maps in states where Democrats had sole control of the redistricting process indicates the tendency to create maps favoring one’s own party is prevalent amongst both Republicans and Democrats.

- Six of the seven states with highly biased maps are considered “battleground states,” meaning they often enjoy competitive elections due to a fairly even partisan distribution. An outsize partisan congressional advantage in these states is entirely at odds with their battleground status, providing strong evidence to suggest the bias in these state’s maps is intentional.

Gerrymandering Distorts Democracy

This level of distortion is not only bad for Democrats, it’s bad for democracy. By padding Republicans’ seat totals, gerrymandered maps mean election outcomes are less responsive to voter preferences. For example, Democrats presently need to gain thirty-four seats to hold the majority in the U.S. House. The authors’ finding that gerrymandered maps give Republicans an extra sixteen or seventeen seats means the Democrats' "magic number" is about twice what it would be under a party-neutral set of maps. In turn, that means Republicans can likely hold the House despite earning fewer votes than the Democrats (as they did in 2012).

Arizona Voters Point the Way to Reform

Wary of this kind of partisan gerrymandering, Arizona voters in 2000 took the task of congressional (and legislative) redistricting away from the state legislature and gave it to a newly-created Independent Redistricting Commission (IRC). The IRC consists of two Democrats, two Republicans, and an Independent Chairperson. The IRC has criteria it must follow in redrawing district lines: they must be in compliance with the U.S. Constitution and the Voting Rights Act; be roughly equal in population; appear compact and contiguous; respect communities of interest; incorporate geographic features such as cities and county boundaries; and should be electorally competitive. Crucially, the IRC is barred from considering where incumbents or candidates live.

According to the Brennan Center analysis, the maps in Arizona, California, and Washington (the three large states that use truly independent commissions) “exhibited much lower levels of partisan bias.” Arizona voters can be proud that they seem to have found at least a partial solution to partisan gerrymandering, and should hope all states swiftly follow suit.