The map of Pennsylvania is about to change in terms of how they elect their Congressional candidates. At least that is what is highly expected after the Supreme Court of Pennsylvania ruled that those maps needed to be redrawn. They took a look at the case and decided that the maps had been drawn in a clearly partisan and unfair way to advantage Republicans in the state.
The GOP got to draw the maps following the 2010 census because they were in power at the state level in Pennsylvania. They did as many majority parties do and drew maps that would advantage their electoral chances in a big way. Simply by clustering Democratic voters together (usually based on race and urban versus rural factors), they could ensure that Democrats would win as few seats as possible regardless of how many votes actually went to Democratic candidates.
The process is called gerrymandering, and it is against the Constitution. Still, parties are the ones who draw the maps, and that makes it very likely that they will draw maps that advantage their own party in the vast majority of cases. This particular case just happened to be terribly advantageous to the Republicans who could claim 13 of the 18 Congressional seats in Pennsylvania despite winning just a slight advantage in the total votes cast for Congressional candidates in 2016.
Buzzfeed News reports that the court has put into place a strict set of guidelines that will have those maps redrawn within approximately one month, or else the court will draw the maps itself. Those are some tight deadlines and tight restrictions on the case, but that is how serious the court is about getting this situation corrected. It is expected that new maps will be available before the general election in 2018 takes place in November.