Democrats are complaining that gerrymandering was behind the party losing 13 of the Pennsylvania's 18 congressional districts last week -- noting Dems outvoted R congressional voters by 75K -- but numbers also show Democrats had registration advantages in 12 seats statewide. So if Democratic voters had strictly pulled the party lever, Democrats would have controlled the delegation 12 to 6 over Republicans instead of being down 5 to 13.
The numbers (based on 2010 registration stats) were passed along by a Harrisburg source. The hidden vigorish is the GOP mapmakers who redesigned the 2012 congressional lines made them tilt GOP by performance, not registration -- they knew, for instance, that 54% of the voters in the new 12th District voted for John McCain for president, despite (as the chart shows below) it being only 37.5% Republican. On Tuesday, the district would vote for Romney over Obama by 17 points (58.5-41.5%) and Keith Rothfus over Dem incumbent Mark Critz by 3 points (51.5-48.5%).