Monopoly Politics Blog Series: Hardening Partisanship in State Legislatures

by Matthew Bugajski, Devin McCarthy // Published April 23, 2014

It’s no secret that Congress is polarized and much of that polarization stems from the partisanship of congressional districts. Most districts are lopsided and all but guaranteed to be won by the same party in election after election. As a result, Members of Congress have little incentive to compromise on legislation or reach across the aisle, leading to gridlock and failure to govern.

But does the same phenomenon occur in our state legislatures?

New data from the Daily Kos helps us answer that question. Daily Kos users, who had previously compiled the 2012 presidential results by congressional district that formed the basis of our Monopoly Politics 2014 report, have now begun tracking 2012 presidential results by state legislative districts. That allows us to assign partisanship ratings to all districts in each of the 29 states for which we have data so far.

As part of its Monopoly Politics 2014 analysis on polarization in Congress, FairVote found that two key factors figure prominently into how Members of Congress vote: their party and the partisanship of their districts. More specifically, the vast majority of Members tend to vote with their party on key votes. Only those who represent “swing districts” – that is, districts with a partisanship favoring their party by less than 53% – or those who represent districts that favor the other party (“crossover representatives”) have any incentive to reach across the aisle and vote with the other side. Despite their crucial role, these legislators are on the decline in Congress: now, crossover representatives comprise just 6% of the House, and only 11% of congressional districts are “swing.”

State legislatures, overall, have similarly low percentages of crossover and swing representatives. The state in the Daily Kos data with the median proportion of swing districts is Virginia, with 12%, and the state with the median proportion of crossover representatives is Hawaii, with 9%. In all 29 states surveyed, 11.6% of districts had crossover representatives.

But there’s a fairly wide diversity of proportions of “bridgebuilders” among these states. For instance, some of the more exceptional cases:

(this analysis excludes those legislators who were last elected before new redistricting maps took effect in 2012)


  • 2% Crossover Representatives
  • 10% Swing Districts

No members of Colorado’s House of Representatives and only two state senators elected since 2012 represent districts that favor the other party. Both senators were elected after a 2013 recall election in which the conservative base was mobilized to oust two Democratic senators who supported gun control. Colorado has the fewest crossover representatives of any state in the data set. Only two of Colorado’s 65 State House districts are swing districts.

West Virginia

  • 52% Crossover Representatives
  • 2% Swing Districts

West Virginia has by far the highest proportion of crossover representatives among the states analyzed, more than twice as many as North Dakota (20% crossover). Of the 64 Democrats elected or reelected in 2012, only 3 came from districts in which Obama received a plurality of the vote. More so than in any other state, West Virginia Democrats still embody the old Southern Democratic model that used to play a major role in American politics. The Democratic Party has continuously controlled both chambers of the West Virginia legislature since 1930.

According to new data compiled by political scientists Nolan McCarty and Boris Shor, however, these Democrats are not particularly conservative. In 2008, Democratic senators in the West Virginia State Senate had an average NOMINATE score (an approximation of the partisan behavior of a representative, with a lower score indicating a more liberal position) of -.25, while nationwide, Democratic representatives in state upper houses had an average score of -.709. Similarly, members of the West Virginia House of Representatives had an average score of -.321, while Democratic representatives had an average score of -.676 nationwide.

On the other hand, almost none of West Virginia’s districts are competitive in presidential elections. If the state follows the trend of the rest of the South toward aligning with the national parties, its legislature will quickly become at least as polarized than Congress.

New Hampshire

  • 15% Crossover Representatives
  • 23% Swing Districts

In New Hampshire, nearly 15% of representatives in the state legislature are crossover representatives. This is partly due to the fact that many of New Hampshire’s districts have multiple legislative seats, with each voter receiving as many votes as seats in the district. Since voters can only allocate one vote per candidate, these districts are mostly swept by candidates from one party. But FairVote has found that in New Hampshire’s primarily-Republican districts with five members or more, Democratic women have often managed to win a seat that would be expected to be won by a Republican.

New Hampshire also has the second highest proportion of swing districts (behind Iowa, at 26%). Both states are swing states in presidential elections and are demographically uniform, making it likely that a given geographical area will have an even partisan split. Similarly, all six congressional districts in New Hampshire and Iowa are within striking distance for both major parties.


There is much more analysis to be done in polarization in state legislatures, and we will be able to draw broader conclusions once more data on post-redistricting district partisanship and legislator ideology becomes available. This preliminary look suggests that though there is some diversity among state legislatures, the pattern of winner-take-all elections contributing to hardening partisanship and polarization is as true at the state level as it is in Congress.