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How can packing and cracking be used to gerrymander voting districts?

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A person ascends the steps of the west facade of the United States Supreme Court Building in Washington, D.C., with its tall columns and a round fountain in the foreground. — Major Supreme Court Cases from the 2025–26 Term The west facade of the U.S. Supreme Court building, Washington, D.C.

In the context of gerrymandering, "packing" and "cracking" are strategic techniques used to manipulate electoral district boundaries to favor one political party or dilute the influence of specific groups.12

Packing: This method involves concentrating voters who are likely to support the opposing party into a single district. By "packing" these voters together, the party in control ensures that their rivals win that specific district by a massive margin, thereby creating a "surplus" of votes that are effectively wasted. This limits the influence of those voters in surrounding districts, where the controlling party can then win more easily.3
Cracking: This technique involves spreading voters who are likely to support the opposing party across multiple districts. By "cracking" a stronghold of the opposition—such as a city or a specific community—and dividing it among several districts, the controlling party ensures that the opposition's voting power is too diluted to achieve a majority in any of them, allowing the controlling party to dominate those areas.4

These practices are central to partisan efforts to secure legislative majorities, a topic that has seen significant legal activity in recent years, including during the 2025–26 term.5