growth that was largely Hispanic and black and create four new congressional districts full of Republican voters. As the plan bounced all over the courts, the map mostly stayed in place for 2012. Texas may have to draw the lines again in 2014, but that depends on the Supreme Court. The case the justices agreed to hear later this term comes from Shelby County, Ala. Post election, the backdrop will be the increasing muscle of Latino and black voters nationwide, with all the demographic evidence of how they helped boost President Obama back into office. But let's not forget who draws the lines for redistricting -- state lawmakers (and in a few states, commissions appointed by the states). These legislators are often chosen in midterm and off-year elections in which the composition of the electorate has tended to be older and whiter than in presidential election years. That helps explain why the Democrats took a beating in 2010. The lesson is that midterm elections can have big consequences. If Democrats ever want to win back the House, they have to get their people to the polls in the off years. And if the Supreme Court guts the Voting Rights Act, it will be more important than ever. Correction, Nov. 10, 2012: This article originally quoted Nathaniel Persily as saying Democrats and Republicans control a certain number of congressional seats. They control the line-drawing process for those seats. ( Return to the corrected sentence.) Correction, Nov. 12, 2012: This article misstated