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.