How Gerrymandering Shapes the Battle for Congress

Votes are not the only factor shaping congressional election results. The boundaries of electoral districts can significantly alter candidates’ chances, making the map itself an important part of the contest.

US states redraw their congressional districts after the census, which takes place every 10 years. The process accounts for population changes and helps keep representation aligned with where people live.

Redistricting is not necessarily a form of manipulation. But when boundaries are drawn to give a political party an advantage, the practice is known as gerrymandering.

That advantage can be created by concentrating opposing voters in a small number of districts or spreading them across several districts where they struggle to form a majority. Either approach can affect how votes translate into congressional seats.

The distinction is between updating electoral maps to reflect population shifts and designing them for partisan gain. Understanding who is grouped into each district is therefore essential to understanding the race for control of Congress.