What accounts for the number of partisan gerrymandering efforts midway through the 10-year census cycle? Brian J. Gaines is a professor of political science at the University of Illinois Urbana-Champaign and the Honorable W. Russell Arrington Professor in State Politics at the U of I System's Institute of Government and Public Affairs. Gaines, who as an undergraduate student served on the staff of the Royal Commission for Electoral Boundaries that redrew British Columbia's electoral map in advance of the 1991 general election, spoke with News Bureau business and law editor Phil Ciciora about redistricting.
How unusual is it for states to revise their electoral maps for a second time since the most recent census?
Mid-decade redistricting is not unprecedented, but it's also not common. Most of the cases in modern history - since the 1960s, say - have been a result of successful litigation challenging the validity of an existing map. There are only a handful of instances of parties in power opting to redraw maps without any legal obligation to do so. On the other hand, there is no firm barrier against doing so. It is a norm, not a law, that redistricting fights should follow the once-every-10-years census calendar.
What is gerrymandering?
Gerrymandering means drawing electoral districts with a specific political purpose in mind, and it takes distinct forms. Racial gerrymandering is usually disfavoring a particular racial group, often a minority. Partisan gerrymandering is choosing lines to help one party and harm another. The jurisprudence on these different kinds of map manipulation is complicated, but a quick take is that the U.S. Supreme Court opted out of policing partisan gerrymandering in its 2019 Rucho decision, so that cases about partisan unfairness of maps are now made in state courts, based on state constitutions.
Federal and state courts continue to judge maps according to how well they proportionally reflect racial divisions in the electorate, with distinct and shifting standards.
Does the public support partisan gerrymandering?
I would say mostly "No," but this is a hard question to answer, and at least some ordinary voters do back redrawing legislative lines to try to predetermine results.
I have done a number of survey experiments in which I ask respondents to choose between maps that are expected to translate an even 50%-50% vote division into either a pretty even 60%-40% seat division, via compact districts, or a very uneven seat division - 75% for one party and 25% for the other - via twisty districts.
When this stylized exercise is applied to a hypothetical state, even the strongest partisans mostly say that they prefer a simple map with tidy districts to one with carefully drawn, twisty districts that help their own party at the expense of the other one.
Similarly, in an Illinois-only study, most respondents liked a hypothetical map with simple districts better than our actual legislative map, which has crazy-looking districts and was quite obviously designed to give Democrats an advantage. Half the time I asked respondents to choose only based on maps, and the other half I also pointed out how the maps differed in expected seats: 11 safe Democratic seats, three toss-ups and three safe Republican seats for the current map versus eight safe Democratic seats, three toss-ups and six safe Republican seats for the alternative.
Republicans and Independents heavily preferred the alternative, but Democrats went from about 2:1 in favor of the alternative without the extra information about seats to 3:2 in favor of the status quo, when alerted to its pronounced pro-Democrat skew.
Real-world events have now created new evidence. Republican legislators in Texas passed a new map that is predicted to deliver five extra Republican seats. The general public did not vote on the matter, but some surveys showed that about two-thirds of Republican respondents approved of the switch.
California's reaction was Proposition 50, a ballot measure throwing out a commission-drawn map in favor of one predicted to give Democrats five more House seats. Proposition 50 was explicitly promoted as retaliation for Texas gerrymandering, to even things up.
Exit polls showed overwhelming support by Democrats (96% yes), strong support from independents (57% yes) and weak, but not negligible, support from Republicans (13% yes). Maybe California Democrats are more willing to win by any means than Illinois Democrats, or maybe the most important difference is that this vote was for real, not a hypothetical choice in a survey - or that Texas had already "started it" and revenge is always hard to resist.
How much time is left for any more states to make new maps before the next election cycle?
Not much. Almost all states follow the federal election calendar and hold regular state legislative races in even years. For U.S. House races, there is no alternative. November 2026 is about 10 months away, but primary elections start much earlier. They can be moved, but at present, five states, including Illinois, have March primaries on their calendars.
Primary dates are not the true deadline, because candidates must announce and launch campaigns before voting takes place. All of those states with March primaries and some other states with somewhat early primaries have deadlines for filing to launch a candidacy that have already passed or are about to pass. Candidates must file to run in districts, so filing deadlines are a reasonable deadline for map revision, without extraordinary measures like after-the-fact extensions or exemptions.
All of that is to say that it's now very unlikely that any other states will make very late entries in the 2025 redistricting brouhaha.
