What is Gerrymandering?
Drawing voting districts to favor the politicians who determine on the boundaries. The term is named for the “Gerrymander” cartoon published by the Boston Gazette in 1812 after Massachusetts Gov. Gerry drew voting districts vaguely shaped like a salamander. 
After the National Census every 10 years, every State looks for population changes that create opportunities to redraw the boundaries of voting districts. When State Legislatures redistrict (other States employ different decision-makers, as explained below) some gerrymander to help the party in power keep or gain more seats. This is one of many reasons why State-level elections are so important. Both Democrats and Republicans gerrymander — the examples here are real.
In this part of Illinois, the Blue party turned a Pink district Light Blue by packing Blue voters into a smaller area and moving excess Red voters into the surrounding Red districts labelled A and B. The smaller size allowed A and B to be joined, thereby eliminating an opposition district completely. D is expanded so its population is roughly comparable to AB. Result: Blue gains 1 Leans Blue district and eliminates 1 Pink and 1 solid Red district.
The cracking example shows where Blue voters had been previously packed into a single district in Northern Florida. After the 2020 Census, the Red party split all the District 5 voters among the neighboring solid Red districts. Then, a Red district was divided in two and one part renamed District 5. Result: Blue loses 1 district while Red gains 1 district.
States may employ an independent redistricting commission, a specific person designated by the State, or the State Legislature to redraw the lines of Congressional Districts and other districts as determined by each State’s laws. As noted above, when State Legislatures redistrict, some gerrymander their districts based on political decisions. State and federal lawsuits have become more frequent in States alleged to have been gerrymandered.
Gerrymandering can be racially or politically motivated. The Supreme Court has found racially-based gerrymandering to be unconstitutional, but political gerrymandering to be constitutional until and unless Congress acts (Rucho v Common Cause 2019) in accordance with its powers under Article 1.4 of the US Constitution to set times, places and manners of elections. Hence the fight for a new national Voting Rights Act as a remedy.
For more information about your State, see
- FiveThirtyEight 2022 Redistricting has maps for every State along with brief commentary on the implications of the change.
- Wikipedia’s 2020 US Redistricting Map showing who determines redistricting in each State.