Perhaps no event will do more to reshape the fight for control of the House than the new congressional map just released by the Pennsylvania Supreme Court. At stake was the fate of a Republican gerrymander that intended to cement a 13-5 Republican advantage in an evenly divided state. Now the Republicans will have little to no advantage at all. Democrats couldn’t have asked for much more from the new map. It’s arguably even better for them than the maps they proposed themselves. Over all, a half-dozen competitive Republican-held congressional districts move to the left, endangering several incumbent Republicans, one of whom may now be all but doomed to defeat, and improving Democratic standing in two open races. Based on recent election results, the new congressional map comes very close to achieving partisan balance.
In general, partisan balance is not usually a goal when redistricting. You could certainly argue that partisan balance and maximizing the number of competitive districts should be among the criteria, but, in general, they are not. Instead, a nonpartisan map usually means a partisan-blind map. It strives for compact districts that respect communities of interest, with little regard for the partisan outcome.
A decision to pursue partisan balance in Pennsylvania would be particularly significant because Democrats are at a clear geographic disadvantage. They waste a lopsided number of votes in heavily Democratic Philadelphia and Pittsburgh; the Republicans don’t waste as many votes in their best areas, and so the rest of the state (and therefore its districts) leans Republican. As a result, a partisan-blind map will tend to favor the Republicans by a notable amount.