These Swing Districts Will Determine Who Controls the House of Representatives

Control of the House is again up for grabs in this year’s elections. The fight will be fierce and expensive, but it will also take place on the narrowest of playing fields.

In the campaign’s final stretch, only 27 of 435 districts — 12 held by Democrats and 15 held by Republicans — are considered toss-ups based on the most recent assessment of a district’s political makeup and candidate strengths and weaknesses by election analysts at Cook Political Report. And just another 16 districts — 6 held by Republicans and 10 held by Democrats — are rated as either leaning Democratic or leaning Republican. In total, barely a tenth of all House seats are toss-up or lean districts this year.

This lack of competitive races is at least in part by design.

In the late 1990s, around 4 in 10 congressional districts voted within five percentage points of the national vote in presidential elections, as calculated using a metric known as the Partisan Voting Index. Researchers refer to these as bellwether districts because they follow national trends. In a country where the national vote for president has been close for decades, these bellwether districts also tended to have relatively close elections.

Flash forward three decades and a growing asymmetry has emerged. On the one hand, presidential elections continue to uniformly produce narrow, single-digit popular vote wins. In 2020, for example, Joe Biden won the national popular vote by fewer than five percentage points, and in 2016, Democratic presidential nominee Hillary Clinton won the popular vote by two percentage points, though she lost the Electoral College.

However, it’s a very different story when it comes to congressional elections. Since the late 1990s, even as presidential elections continued to be close, the number of congressional districts where district-level presidential results more or less matched close national results has fallen by more than half. More than 80 percent of congressional districts are now decidedly red or blue.

In the vast majority of these congressional districts, the Democratic or Republican candidate for president — and almost always the prevailing congressional candidate — win by landslide margins. In 2020, for example, Biden carried 167 congressional districts by 15 or more percentage points, and Donald Trump carried another 149 districts by the same margin. These districts together make up a whopping 73 percent of all current House seats.

Unsurprisingly, the decline in the number of bellwether districts tracks the growth in single-party control of the redistricting process in states and the corresponding rise in aggressive gerrymandering.

Consider the 2024 toss-up districts. Of the toss-up districts that will play an outsized role in which party controls the next House, 17 of 27 — or nearly two-thirds — were drawn by commissions, courts, or under divided control of government. Another 3 are in New York, where congressional districts were redrawn to comply with anti-gerrymandering standards in the state constitution. These 20 districts plus Alaska’s single district make up nearly 80 percent of all 2024 toss-ups.

Independent commissions, where everyday citizens rather than politicians draw maps, have played an especially big role in the preservation and creation of competitive districts. Despite drawing only 19 percent of congressional districts, independent commissions drew 41 percent of districts that are rated as toss-ups in 2024. Such commissions are currently used in four states: Arizona, California, Colorado, and Michigan. This fall, voters in Ohio will decide whether to create one in the Buckeye State through a state constitutional amendment.

By comparison, redistricting processes under control of a single party drew 60 percent of congressional districts that will be used in this year’s election, but only a third of toss-up districts and just 37 percent of all districts rated either lean or toss-up.

States where Republicans had unchecked control of the redistricting process are particularly stark when it comes to competition. GOP-controlled states drew 184 of the districts that will be used in this year’s election — far more than any other map drawer. But only five are toss-ups, with another two districts, both held by a Democrat, were rated as lean Democratic. Worse, the competitiveness of one of the Republican-drawn toss-up districts comes not from the application of equitable principles but from the racially discriminatory gerrymandering of an eastern North Carolina district that has been represented by a Black Democrat since the early 1990s.

Democrats with unchecked control of the redistricting process did somewhat better. Of the 75 districts they drew, four are toss-ups, with another five rated as leaning Democratic.

The role played by commissions and courts is not a new phenomenon. For example, when Democrats flipped control of the House in 2018, nearly three in four of the districts that gave them a majority were ones drawn by more neutral map drawers. Likewise, when Republicans narrowly regained control of the House in 2022, commission-drawn maps in places like California were essential to their path.

The regional story is especially stark. The South is the country’s largest and fastest-growing region, but, in 2024, has just two toss-up districts — a district in Virginia drawn by a court and a district in North Carolina designed to gerrymander a Black Democrat out of a seat.

This lack of competition is remarkable. The burgeoning South is home to some of this cycle’s most competitive presidential and Senate battlegrounds. Indeed, the fastest growing states of the South have an abundance of the type of increasingly purple suburbs that anchor competitive congressional districts elsewhere in the country. Fifty-four percent of North Carolina voters, for example, are suburbanites. The highly educated, rapidly diversifying suburbs of cities like Atlanta, Charlotte, Dallas, and Houston should be ground zero in the battle for the House, but races there have effectively already been decided thanks to gerrymandering.

But the lack of competition in southern states is not surprising. Partisan control of map drawing remains the norm in the South, and Republicans, who had sole control of the redistricting process in all but two southern states after the 2020 census, used it aggressively to redraw districts in places where politics had become more competitive or were on the verge of doing so. In Texas, for example, they drew a district that joined parts of the suburbs of Dallas with parts of rural Texas along the New Mexico border nearly 500 miles away. Outside of Houston, they similarly dismantled a diverse, multiracial district that had been a toss-up in recent election cycles. With limited exceptions, state courts in southern states have failed to police these abuses.

To be sure, even with fair redistricting processes, not every district would be competitive. Geographic sorting and a hardening of the political identity of a growing number of Americans mean many parts of the country are simply too deep blue or deep red for there ever to be much competition, regardless of how fairly district lines are drawn. Likewise, candidate quality, fundraising, incumbency advantage, and the national electoral environment may make theoretically competitive districts uncompetitive.

But with few checks on partisan abuses, the path to a House majority now runs largely through districts drawn by commissions, courts, and divided governments, or in states with strong legally enforceable map drawing rules.

Without the passage of federal reforms such as the Freedom to Vote Act and John R. Lewis Voting Rights Advancement Act — as well as state-level reforms — this is only likely to continue into the foreseeable future.