Legislative district lines are redrawn every ten years to account for demographic changes among the population based on census data. Over time, the process of redistricting has become highly politicized and is often criticized for cutting constituents out of districts to favor a given candidate. The Brookings Institute describes the process as, "among the most self-interested and least transparent systems in American democratic governance."
In the lead up to Tuesday's election, public policy experts worried that redistricting efforts would greatly change the course of races for the House of Representatives. In states like Michigan, Virginia, Ohio and Pennsylvania, there were 59 house seats up for grabs. Democrats won 17 of those seats, or 28.8 percent, even though President Obama received more than 50 percent of the vote in each of those states.
Nate Persily, a professor of law and political science at Columbia University who works closely on redistricting issues, explains how redistricting impacted the 2012 election.