What is apportionment gerrymandering?

Gerrymandering is a way of redrawing lines in a voting district to favor a candidate/political opponent and to hurt their opponent's chances of winning. For instance, a Republican could draw district lines to include many Republican voters into one district. They could also draw the district lines to split up the Democrat voters, making it difficult for them to ever be a majority of the district. Often, gerrymandering is obvious because of the strangely-shaped districts.