For the last decade in particular, Republicans have leaned heavily on a radical form of district drawing in order to maintain power.
Democrats vastly outnumber registered Republicans in the Keystone state, yet Republicans enjoy control of 13 of the state's 18 Congressional seats. And a lot of that is because of radical gerrymandering.
Meanwhile, Donald Trump has become personally invested in a Pennsylvania special election set for March 2018. The White House is scrambling to make sure GOP candidate Rick Saccone fends off a young Democratic challenger, Conor Lamb, a Marine Corps veterans, in the 18th Congressional District.