How Gerrymandering and Fair Maps Affected the Battle for the House

On the surface, the 2024 fight between Democrats and Republicans to control the House resulted in continuation of the status quo.

In 2022, Republicans won a net of nine Democratic seats to gain a narrow, and at times dysfunctional, majority of 222–213. This year, Republicans retained control, winning an only slightly smaller majority of 220–215. (With the resignation of Florida Rep. Matt Gaetz and two more expected vacancies in January because of Trump administration appointments, that majority is expect to drop further temporarily to 217–215.)

But dig a little deeper, and the 2024 election offers important insights about the power of gerrymandering, the impact of redistricting reforms, and the role that courts play in fair outcomes (for both good and ill).

Heading into Election Day, only 27 House districts were categorized as competitive by Cook Political Report. Other election forecasters had even fewer districts on their lists of tossup and lean districts. In the end, the field proved just about as thin as expected.

Only 37 districts — 22 won by a Democrat and 15 won by a Republican — were decided by five or fewer percentage points, and, of those, just 19 districts flipped between parties.

By contrast, more than 4 out of 5 districts — 169 districts won by a Democrat and 198 districts won by a Republican (90 percent of the GOP House majority) — were decided by comfortable margins of 10 or more percentage points. In fact, the vast majority of these districts were not just safe but ultra-safe.

All told, nearly 6 in 10 House districts — 112 carried by a Democrat and 132 carried by a Republican — saw the winning candidate prevail by 25 or more percentage points. These districts are so safe, it would take an unprecedented tsunami-sized wave election to flip them. Strikingly, there were more districts where the candidates prevailed by a fortress margin of 40 to 50 percentage points (55 of them) than districts where the outcomes were decided by five or fewer points (37).

To be sure, this lack of competition is not entirely due to the manipulation of district boundaries. Some parts of the country are simply too deep blue or red for even the fairest of map drawers to be able to craft many competitive districts. But who was in charge of the map-drawing process did matter.

Consider, for example, the decided lack of competitiveness in maps drawn by Republican-controlled governments.

Republicans drew 184 districts — 42 percent of all congressional districts and far more districts than any other kind of map drawer. Republican-controlled states, moreover, include virtually all the boom states of the South, which are full of the ideologically diverse, “purplish” suburbs of the sort that anchor competitive districts in states like California, Nebraska, and New York. Indeed, in 2018 and 2020, before the most recent round of redistricting, the suburbs of southern states like Georgia and Texas were home to some of the country’s most competitive House races.

But this year, using maps redrawn after the 2020 census, states where Republicans drew lines had just 8 districts that were decided by five or fewer percentage points. Put another way, in 2024, just 4 percent of districts in states where Republicans held the map-drawing pen featured close races.

By contrast, independent commissions drew just 82 of the 435 House districts (less than half as many as Republicans drew) but were responsible for 12 competitive districts. On a percentage basis, over three times as many districts were competitive in states where independent commissions drew maps as in states where Republicans drew maps.

The region and party disparities for competitive elections are equally striking.

In the South, where Republicans controlled almost all of the line drawing, just 2 districts out of the 111 won by a Republican were decided by fewer than 10 points and only 1 district — a district in Virginia adopted by a court after redistricting deadlock — by fewer than 5 points. By comparison, 75 of those same 111 southern districts were decided in favor of GOP candidates by super-safe margins of 25 points or more.

This trend is not a one-off. The paucity of narrowly decided races closely matches outcomes in 2020 and 2022 under different sets of maps and varying electoral conditions.

But, ironically, Republicans’ creation of so many super-safe GOP districts may have the limited the scale of Republicans’ 2024 wins.

This year, Republicans won the total number of votes cast nationally in House races by just over a point more than they won it by in 2022. Yet, despite having a better year, Republicans emerged with a slightly reduced majority. One reason for this seeming anomoly is the way that Republicans gerrymandered in much of the country in the last round of redistricting.

Take Texas, for example. Heading into redistricting in 2021, Republicans in Texas were faced with an electorate that had become steadily more Democratic over the course of the preceding 15 years — a product both of the state’s increasing diversity and political shifts in its fast-growing suburbs after the election of Donald Trump. Indeed, in 2018, Democrats surprised Republicans by flipping two suburban districts thought to be safe, and Democratic Senate challenger Beto O’Rourke come within three percentage points of upsetting Republican incumbent Ted Cruz, the strongest performance for a Democrat in Texas in two decades.

Confronted with these seemingly relentless headwinds, when it came time to redistrict, Republicans chose not to target any Democratic-held seats, including recently flipped seats. Instead, their gerrymanders had a different goal — to protect GOP incumbents.

To accomplish this end, GOP map drawers in Texas redrew districts to pack Republican voters into districts where the GOP candidate is guaranteed to win by overwhelming margins. While undoubtedly welcome by Republican incumbents, the strategy produced the side effect that in a good Republican year, there are precious few swing districts to pick up. Gerrymandering may have made Republican seats safe, but by concentrating Republican voters in heavily Republican districts, it had the parallel effect of also making Democratic seats safe ones.

Paradoxically, this play-it-safe strategy by Republican line drawers in Texas and other states may help Democrats win back the House in the future because it blunts the size of Republican House majorities.

And the hopeful news for Democrats nationally is that while this decade’s maps contain an abundance of safe districts and a scarcity of competitive districts, there are just enough of the latter to give the party multiple reasonable paths back to a majority, especially if future election cycles prove to be more like 2018 or 2020 — strong Democratic years — rather than a year like 2024 with its significant pro-Republican headwinds.

Gerrymandering impacts elections, but rarely in as vivid a fashion as 2024.

After the 2022 midterms, five states adopted new congressional maps. In three states, maps became less biased. In the other two, however, maps either became more gerrymandered or remained the same — and these two states would prove decisive in 2024.

North Carolina

Post-midterm gerrymandering had the biggest impact in North Carolina, where last year the state supreme court abruptly overturned recent precedents that had previously recognized partisan gerrymandering claims under state law.

In 2022, voters in the Tar Heel State used those precedents to successfully challenge an extreme Republican gerrymander of the state’s congressional map, winning replacement of a heavily skewed Republican-drawn map with fairer districts drawn by a court-appointed special master. Under that revised map, North Carolinians elected seven Democrats and seven Republicans in that year’s midterms. But the victory for fair maps proved short-lived.

In the same election, conservatives won a majority on the state supreme court, and Republican lawmakers swiftly asked the court to reconsider its anti-gerrymandering precedents. The court agreed to do so and did a head-spinning U-turn, holding that, going forward, partisan gerrymandering claims under state law, like their counterparts under federal law, would be political questions off limits to courts.

Free to gerrymander, Republicans redrew the map, replacing the special master’s 7–7 map with a legislatively drawn map that elected 10 Republicans and 4 Democrats in 2024.

In fact, Republicans’ gerrymander was so aggressive that the shift of a mere 3,152 votes in the state’s 1st Congressional District, long-represented by a Black Democrat, would have produced a delegation with 11 Republicans and just 3 Democrats. If the Democratic incumbent in that district decides to retire in the future or if Democrats have a particularly bad year,the gerrymandered map may yet produce a 11–3 result before the decade is out. 

That’s a wildly skewed outcome for a perennial battleground state like North Carolina. In 2024, North Carolina Democrats won over 46 percent of the vote in congressional races (after adjusting for uncontested races), but a mere 29 percent of congressional seats.

This degree of skew in the results is not the result of political geography. In some states, such as Massachusetts, the distribution of voters makes it impossible to draw a map that is roughly proportional while complying with the requirements of law and other neutral map-drawing rules.

Not so in North Carolina. The special master’s map is just one real-world example of a fairly drawn map that achieves proportionality while complying with neutral districting principles. But it not the only one. Computer simulated maps from researchers at Harvard show that it is easy to come up with thousands of other alternatives that comply with strong anti-gerrymandering standards like those in the proposed federal Freedom to Vote Act.

Importantly, these carefully engineered advantages are not limited to 2024, but are all but certain to endure for the rest of the decade. In all 10 of the North Carolina districts won by Republicans in 2024, the GOP candidate not only won but prevailed by double-digit margins large enough that it will be hard for Democrats to ever flip the seats, even if their party performs substantially better at the ballot box.

Georgia

Gerrymandering in Georgia after the 2022 midterms also played a role in helping Republicans keep control of the House.

In Georgia, a federal court ordered creation of a new Black majority district to bring the state into compliance with the Voting Rights Act. Republican lawmakers did as the court ordered and drew the required new Black district. But they offset the new district —  almost certain to elect a Black Democrat — by simultaneously dismantling a very diverse, multiracial district in the Atlanta suburbs that elected a Democrat in 2022.

The newly gerrymandered district performed as expected in 2024 and elected a Republican by a 30-point margin. More important, in a tight race for the House, the new district kept the Peach State’s congressional delegation at nine Republicans and five Democrats.

Absent new gerrymanders in North Carolina and Georgia, Democrats likely could have won a two-seat majority of 219–216, before any vacancies.

And the impact of gerrymandering in these two states on control of the House doesn’t factor in the impact of gerrymandering elsewhere. A recent Brennan Center study found that gerrymandering, mostly in the South and Midwest, gives Republicans a significant net advantage this decade.

Maps in Florida and Texas have especially large multi-seat skews, but smaller skews in states like Tennessee, South Carolina, and Utah also made it harder for Democrats to reclaim a majority.

As in past cycles, who drew the maps is a big part of the reason why Democrats, despite being disadvantaged by gerrymandering, were able to keep the fight for the House close.

Indeed, notably, of the 19 districts that changed parties this election, 13 were created through mapping processes that tend to produce fairer, less biased maps.

Broken down, 5 of 19 flipped districts were created by independent commissions, 5 under court supervision after legislative deadlock or as a result of litigation, and 3 by a legislature subject to strong, judicially enforced limits on partisan gerrymandering. Add in Alaska, which has only one district for the entire state, and 74 percent of flipped districts were either in states that used fairer map-drawing processes or else didn’t have to redistrict because they had only one seat. Though Democrats didn’t win the House, these districts counteracted gerrymandering elsewhere and kept them in the game.

The 2024 election was also a striking illustration of the growing importance of the South in deciding who controls the House. The region, which has grown to be the country’s most populuous by far, is an especially critical anchor for any Republican majority in the House.

In 2024, the region provided Republicans 111 of their 220 seats — more than half of GOP seats in the next House and the largest number of Republican seats from the region in history.

In contrast, Democrats won 171 of 280 districts outside the South — a 31-seat majority — including the bulk of seats in the Northeast and West and around 4 in 10 seats in the country’s other non-southern regions. By comparison, the party won just 28 percent of districts in the South.

The edge that the South gives Republicans in many ways resembles the one the region gave Democrats from 1955 to 1995, when southern support helped Democrats hold the House continuously for four decades straight. If anything, the edge is greater.

Today, nearly 4 in 10 Americans live in the South, compared to just over a quarter in 1960. The region’s high level of support for Republicans and its high levels of racially polarized voting help give Republicans a significant natural advantage. But that advantage is further exacerbated by some of the country’s highest levels of partisan gerrymandering and a continuation of racially discriminatory line drawing in many places.

And while voters have challenged discriminatory maps in court, progress has been uneven and slow. So far, southern state courts, unlike their counterparts in the rest of the country, have been unwilling to enforce any limits on excessive gerrymandering. Claims challenging maps for racial discrimination, likewise, often end up bogged down in litigation that can take the better part of a decade to resolve, providing scant time for voters to enjoy new maps before the next round of redistricting. Worse, map drawers are often able to evade liability by claiming that maps that discriminate against voters of color do so on the basis of voters’ partisanship (their support for Democrats) and not their race.

This means that, absent federal intervention through bills like the Freedom to Vote Act and John R. Lewis Voting Rights Advancement Act, the advantage the fast-growing South provides Republicans is likely to grow after the 2030 census when the region is projected to gain 11 congressional seats.