Gerrymandering = a political party draws the borders of the district to give itself an overwhelming majority such that no challenger from another party has a se

Gerrymandering = a political party draws the borders of the district to give itself an overwhelming majority such that no challenger from another party has a serious chance of winning in the election. Thus, an open primary is useless without ending gerrymandering: voters in the gerrymandered district would have the choice between multiple candidates from multiple parties, but the voters have been selected to choose candidates of Party Z. Candidates of Party Z may split the vote in the primary, against a candidate from Party A who takes the plurality (say, 40%, or all non-gerried votes). However, this challenger would lose to the winning Party Z candidate in the election. In states with open primaries but no gerrymandering restrictions, the districts are generally designed such that the party out-of-power does not have the vote in any particular district to carry a plurality in the primary. Generally, this is accomplished by gerrying all of the minority party's voters into a single district where that party has an obscence supermajority.