While gerrymandering is an ancient practice, it has been turned into an artform in recent times. the gerrymander in Wisconsin is so great that even in 2012,  a year where Obama won the state by 7 points, Republicans still won 60 seats. It favors Republicans by 14 points, which is a margin so large even a huge national Democratic wave wouldn't overcome it. Wisconsin isn't the only state to be greatly gerrymandered, Michigan, Ohio and North Carolina are as well. In the South, party is historically tied to race, blacks almost always vote Democrat, thus any change to limit African American political power, by extension is also a change to limit Democratic political power.  The Voting rights Act requiring pre-clearance was a good idea, but it did not go far enough. it needed to address all states with a history of  denying minorities the right to vote. Wisconsin would have not qualified under the original rules, but its actions since 2010 mean it would qualify now. Gerrymanders need to go.