http://www.dailykos.com/stories/2016/10/27/1579905/-These-three-maps-show-just-how-effectively-gerrymandering-can-swing-election-outcomes
"Following the 2010 census, Republicans crammed as many Democrats as they could into just three districts, taking in parts of dark-blue Charlotte, Durham, Greensboro, Raleigh, and other cities, along with black voters in the rural northeast, almost all of whom vote Democratic. When Republicans couldn’t pack in Democrats from other liberal cities like Asheville in western North Carolina or Wilmington in the southeast, they cracked them between two seats containing other heavily Republican turf. With surgical precision, Republicans spread out their own voters almost perfectly evenly among the other 10 districts, making sure that none would be either blue enough to be vulnerable or too heavily tilted to the right such that Republican votes would “go to waste.” Although Mitt Romney only carried North Carolina with 51 percent of the two-party-only vote, he won 10 districts with between 56 percent and 62 percent. On the other hand, Romney won less than 30 percent in all three Democratic vote-sinks."
