Both parties entered the latest redistricting cycle seeking to press their advantages where they could.
The first election held under the new lines showed both succeeded - though Democrats had their most ruthless gerrymanders thrown out in the courts and the GOP did not, giving Republicans an edge that just might have carried them to a narrow House majority.
"The Democrats' redistricting strategy was right. I think it worked," said Kelly Ward Burton, the president of the National Democratic Redistricting Committee, which oversaw the party's 2022 mapmaking.
Democrats' excesses in New York and Maryland - where they drew maps to excise the few Republican seats remaining - were checked by the courts, even though similarly gerrymandered GOP maps were allowed to stand by conservative jurists. But independent commissions and strategic Democratic maneuvering did help blunt larger Republican gains.
"If they would have been able to do everywhere what they did in Florida," Ward Burton said of Republicans, who netted four districts in the state, "we would be having a totally different conversation about the House right now."
Now that the 2022 midterms are in the books, here are five takeaways about how the map lines drove the results - and what comes next.
Redistricting probably did give Republicans control of the House
After a shockingly disappointing election night, Republicans will have a razor-thin majority of no more than five seats (and maybe as small as four). A margin that small means that the GOP could not have reclaimed control without their redistricting advantage.
Republicans drew several red districts in states where they controlled the redistricting process: one each in Tennessee, Texas and Georgia, and three in Florida. Without them there would be no GOP majority. Their machinations forced Reps. Jim Cooper (D-Tenn.); Carolyn Bourdeaux (D-Ga.); Stephanie Murphy (D-Fla.) and Charlie Crist (D-Fla.) into early retirements. Rep. Al Lawson (D-Fla.) ran in a new GOP-leaning district and lost to Rep. Neal Dunn (R-Fla.) by 20 points.
In blue states, Democrats netted themselves a seat each in New Mexico and Illinois - not enough to offset GOP gains.
The GOP also gained new safe districts through reapportionment in three states that added congressional seats: Texas, Montana and Florida. But Democrats largely matched them with gains in new seats in Colorado, Oregon and North Carolina - though some of those maps were drawn by courts or commissions.
Republicans notably declined to aggressively redistrict in several other states where they had total control to take out Reps. Frank Mrvan (D-Ind.), Emanuel Cleaver (D-Mo.) and John Yarmuth (D-Ky.). Those decisions, which irked some national strategists, could have given the GOP more of a cushion but also potentially provoke more lawsuits.
Democrats didn't create dummymanders
Blue-state Democrats headed into election night with a persistent concern: Did they stretch their voters too thin? Would a bad environment gut their delegations in Oregon, Nevada, Illinois and New Mexico?
The answer was a resounding no.
Democrats didn't accidentally create any "dummymanders" - a term used to describe maps that end up harming the party that drew them. In contrast, Democratic-drawn maps performed remarkably well. Next year Republicans will hold just six of the 43 districts that were drawn by Democrats.
For example, in Nevada, Democrats pulled friendly voters from Rep. Dina Titus' Las Vegas-centered district to shore up fellow Democratic Reps. Susie Lee and Steven Horsford in a move that prompted a foul-mouthed rebuke from Titus. Former President Joe Biden would have carried the districts by high single-digit margins. All three members survived.
In New Mexico, some operatives feared that Democrats may have endangered Democratic Rep. Teresa Leger Fernandez when they reshuffled the state's lines to target GOP Rep. Yvette Herrell's southern district. But Herrell narrowly lost to challenger Gabriel Vasquez as both Democratic incumbents won by double-digit margins, giving Democrats all three seats in the state.
Illinois was perhaps the biggest redistricting coup for Democrats. They reduced the GOP footprint to just three districts, shored up retiring Democratic Rep. Cheri Bustos' district and netted a new seat anchored in Springfield. In anticipation of a possible Republican wave, Democratic groups threw some last-minute money to protect Reps. Sean Casten and Lauren Underwood, but both ended up winning by 8 points.
Democrats flirted with disaster the most in Oregon, which hosted three battleground races. Republicans did flip a Portland-area district that was open after moderate Rep. Kurt Schrader fell to a progressive primary challenger. But Democrats held onto retiring Rep. Peter DeFazio's district and captured a new district created in apportionment. Rep.-elect Lori Chavez-DeRemer (R-Ore.), who will succeed Schrader, will be a top 2024 in a seat that Biden won by nearly 9 points.
The courts hurt Democrats but boosted the GOP
New York was Democrats' biggest disaster on Election Day. They won only 15 congressional districts compared to 11 for Republicans - an increase of three seats for the GOP, even though the state lost a seat in reapportionment. A slew of statewide races were also closer than Democrats had anticipated.
But the party's challenges in congressional races started much earlier when the state's highest court struck down new maps in April that were drawn to favor Democrats. The new maps established the following month forced incumbents to scramble, most notably DCCC Chair Sean Patrick Maloney, who opted to run in the new 17th District, where more than 70 percent of voters were new to him. Maloney ultimately narrowly lost to Republican Michael Lawler in November.
Redistricting is not solely responsible for Democrats' losses in New York, but the episode is one example of how courts in blue states declined to allow Democratic gerrymanders to stand. In Maryland, courts similarly threw out a Democratic gerrymander to force a more neutral map, although the ultimate electoral impact was less there as Rep. David Trone (D-Md.) held on in a competitive seat that his party had unsuccessfully sought to make safer.
Democrats' inability to gerrymander Maryland and New York stands in stark contrast with states such as Florida, where courts declined to block Gov. Ron DeSantis' aggressive redistricting plan that allowed Republicans to pick up four seats despite an anti-gerrymandering amendment to the state's constitution passed by voters a decade ago that states districts should not be drawn to advantage a political party, along with lawsuits that dismantling Lawson's North Florida seat stripped away a district where Black voters could elect a candidate of their choice.
The 2024 map
Democrats have a relatively easy task in drawing up targets for 2024. Although court fights could shift the maps in a few states, more than a dozen Republican incumbents will be running in districts Biden won with the Democratic president himself likely to be on the ballot.
Some of those Republicans are incumbents who survived this cycle despite being top Democratic targets - including Reps. Mike Garcia (R-Calif.) and Don Bacon (R-Neb.) - and battle-tested incumbents such as Rep. Brian Fitzpatrick (R-Pa.) who will be tough to oust. But the group also includes newly elected members who took advantage of poor Democratic performances in states such as New York, where six Republicans will represent districts won by Biden.
By contrast, only five Democrats - Reps. Jared Golden of Maine, Matt Cartwright of Pennsylvania, Mary Peltola of Alaska, Marie Gluesenkamp Pérez of Washington and Marcy Kaptur of Ohio - represent districts won by then-President Donald Trump in 2020.
House Majority PAC, Democrats' top congressional outside group, released a preliminary 19-district list of districts it would try to flip in 2024 full of Republicans in Biden-won districts. Among its targets: Garcia, Bacon, Fitzpatrick, Lawler, Chavez-DeRemer, along with Reps. David Schweikert (R-Ariz.), Young Kim (R-Calif.), Michelle Steel (R-Calif.) and Reps.-elect Juan Ciscomani (R-Ariz.), Tom Kean Jr. (R-N.J.), George Santos (R-N.Y.), Anthony D'Esposito (R-N.Y.), Marc Molinaro (R-N.Y.) and Jen Kiggans (R-Va.).
The next redistricting battlefields
Several states could see another round of redistricting before 2024 as their current maps face legal challenges that were not resolved this year - although some states will depend on future court rulings.
In Ohio, the midterm elections were carried out under Republican-drawn maps that the state Supreme Court had deemed an illegal gerrymander - although Democrats actually managed to gain a seat anyway. The state's redistricting commission is tasked with drawing new maps ahead of 2024. If it ends up in front of the state Supreme Court again, it might be handled differently, as the Republican justice who had sided with Democrats against the original maps retired this year.
Earlier this year, a divided U.S. Supreme Court blocked a district court's ruling that Alabama should be forced to draw a new map with a second majority-black district, deeming such a move would come too close to the primary election. When the court heard the full case on its merits in October, the justices seemed skeptical of Alabama's race-neutral interpretation of the Voting Rights Act. But several conservative justices also seemed wary of the claims from civil rights groups, and the high court has generally not been friendly to challenges based on the VRA in recent years.
Maps in Texas and Florida have also faced challenges on the basis of racial gerrymandering, although it's unclear whether either state will be forced to redraw its maps.
But a second case before the U.S. Supreme Court could have broad implications for redistricting. The high court next month will hear oral arguments in Moore v. Harper, which argues that North Carolina's maps - created by a court-appointed special master after the state Supreme Court ruled the maps drawn by the Republican-led legislature were an extreme gerrymander - are unconstitutional on the basis that only state legislatures, not state courts, can decide district lines.
A ruling in favor of the Republican legislators who challenged North Carolina's special maste- drawn-map could potentially open up avenues for legal challenges to maps in a range of other states where courts were involved. But the high court could also rule against them and let North Carolina's maps stand.