One of the most important results of Tuesday's election occurred below the governor, Senate, and House lines on the ballot. The Republicans overwhelmed the Democrats in state legislative races all across the country, picking up more than 500 seats and flipping a dozen and a half legislative chambers.
The following charts list the number of seats the Republicans gained (or, in a few cases, lost) in every legislative chamber in the country, except those that did not have elections this week (Mississippi, New Jersey, and Virginia), Nebraska (which has a non-partisan unicameral legislature), and those for which sufficient returns were not available as of this writing (New York, Oregon, and Washington).
Let's run through the list by region, starting with the Northeast.
Now the South.
Now the Midwest.
Now the West.
We can combine the gubernatorial results with the state legislative results to get a read on which parties control which state governments. The following maps are from the National Conference of State Legislatures. This was the picture before election day.
And now after election day.
This is a hugely important advance for the Republican Party. For two reasons. First, state legislatures are like the minor leagues of baseball. In future years, these gains will yield a new crop of Republican recruits for the House, the Senate, and maybe even the White House itself.
Second, next year state governments will begin redrawing the House legislative lines, and this offers the Republican party an advantage that it has not enjoyed in 50 years. As Sean Trende notes:
[D]uring the 60s, 70s, and 80s, the Democrats controlled redistricting. Most of these seats were in the South, where state legislators deftly drew Congressional boundaries to slow down the Republican advance.
This all changed in 1990. Although Republicans controlled almost no seats in redistricting, Democratic control was reduced by the good GOP gubernatorial year of 1986. These Governors forced compromises where the GOP made advances in redistricting that had been impossible in previous decades.
In addition, a new interpretation of the Voting Rights Act limited the ability of Southern Democrats to gerrymander their states effectively. They tried, mightily, but by 1994, the GOP was riding a wave into control of seats.
So, 2000 saw the smallest disparity between the parties in redistricting in decades. Democrats chose to implement conservative incumbent-protection plans in two of their largest states, Illinois and California. They imposed partisan plans in Georgia, Maryland, North Carolina and Indiana, but with Illinois and California neutralized, the GOP was able to respond in kind in Pennsylvania, Ohio and Michigan, leveling the playing field between the parties for the first time in decades. In 2006 that playing field was tilted toward the GOP, as they engaged in the first non-court-ordered mid-decade redistricting since New York in 1970, undoing Democratic plans in Colorado (later overturned by the state courts), Texas and Georgia.
That balance led to the situation today, when the GOP was able to overtake the Democrats. By having a wave wash ashore in a redistricting year, the GOP controls redistricting in a near-majority of House seats. The Democrats would have control of California, but the state approved a non-partisan redistricting commission to oversee its anticipated 53 seats; Florida had the inverse effect on 26 seats the GOP would otherwise control.
The political effects of redistricting are somewhat quantifiable. Trende notes that the 2000 cycle was one during which the GOP pulled to rough parity with the Democrats. On Tuesday, the Republicans appeared to have won roughly the same share of the House popular vote that they won in 1994, yet the party picked up approximately 13 more seats.