Editing Gerrymandering (section)

===Incumbent gerrymandering===
Gerrymandering can also be done to help incumbents as a whole, effectively making every district a packed one and greatly reducing the potential for competitive elections. This is particularly likely to occur when the minority party has significant obstruction power: unable to enact a partisan gerrymander, the legislature instead agrees to ensure its own reelection.

In an unusual occurrence in 2000, for example, the two dominant parties in California [[Redistricting in California|cooperatively redrew]] both state and federal legislative districts to preserve the status quo, insulating the incumbents from unpredictable voting. This move proved completely effective, as no state or federal legislative office changed party in the [[2004 U.S. House election|2004 election]], although 53 congressional, 20 state senate, and 80 state assembly seats were potentially at risk.

In 2006, the term "70/30 district" came to signify the equitable split of two evenly split (i.e. 50/50) districts. The resulting districts gave each party a guaranteed seat and retained their respective power base.

Since the first handshake deal in 1981, whereby Republicans informally controlled the state senate redistricting process and Democrats informally controlled the state assembly redistricting process, New York has experienced some of the nation's least competitive legislative elections. One study by the Brennan Center for Justice at New York University Law School found that over one 10-year period, as many members of the state legislature died in office as were defeated in elections. More than 99% of the incumbents contesting a primary or general election won their races.<ref>{{Cite book |last=Seabrook |first=Nick |date=2022 |title=One Person, One Vote: A Surprising History of Gerrymandering in America |location=New York |publisher=Pantheon Books |pages=232–233 |isbn=978-0-593-31586-6 |oclc=1286675891}}</ref>