Question

Why do political parties most often try to gerrymander voting districts?

to gain a political advantage
to ensure an equal chance for all candidates
to prove they deserve the voters’ support
to keep each voting district the same shape

Answer 1

To gain a political advantage.

Parties gerrymander by drawing district lines to concentrate (pack) or dilute (crack) opponents’ voters so they win more seats than their raw vote share would merit.