http://www.salon.com/2017/05/06/gerrymandering-did-this-how-the-gops-redistricting-master-plan-brought-us-trumpcare-even-though-most-people-hate-it/
"Here’s why. Gerrymandering helped lock in GOP control of Congress. In 2012, Americans re-elected Barack Obama, strengthened the Democratic majority in the U.S. Senate, and delivered 1.4 million more votes to Democratic House candidates than Republicans. The GOP, however, maintained control of the House, 234-201. It was an exceptionally rare example of the party with the most votes not getting the most seats — but it was no fluke. Far from it. It was part of a plan called the Redistricting Majority Project, or REDMAP for short, which is exactly what it created. Republicans set out in 2010 to take control of key legislative chambers in states like Michigan, Ohio, Wisconsin, Pennsylvania and North Carolina, all with an eye toward locking Democrats out of the room and taking complete control of drawing all-important district lines. Locking Democrats out of the room is literally what Republicans did in Ohio — where GOP officials moved redistricting headquarters out of the state capitol and into a suite at the Doubletree dubbed the Bunker — and in Wisconsin, where operatives set up at a Madison law firm and claimed that attorney-client privilege allowed them to shroud the process in secrecy. Here’s how well it worked: There are 435 House districts. In 2011, Republicans were able to draw 193 of them by themselves. Democrats? Just 44. That’s nearly a five-to-one advantage. Princeton professor Sam Wang has shown that Republicans likely gained at least 12 seats due to gerrymandering in 2012. Look how the election played out in just a handful of blue states and swing states on these new maps: In Pennsylvania, voters cast 100,000 more votes for Democratic House candidates than Republicans. But by surgically crafting district lines to pack Democrats into as few seats as possible, Republicans won 13 of 18 races. In Michigan, Democrats seeking the House won 240,000 more votes than GOP competitors. Republicans, however, won nine of 14 seats."
