Why gerrymandering matters in the 2026 US midterm elections

The battle for control of the US House may be influenced before voting begins. Across several states, politicians are redrawing congressional districts to improve their party’s chances in the 2026 midterm elections.

This practice is called gerrymandering. It refers to manipulating electoral boundaries to favour one political party or reduce the influence of a specific community’s votes.

The issue has drawn attention as several states redraw their congressional maps midway through the 10-year redistricting cycle. Such revisions are typically carried out after the national census, rather than shortly before a major election.

How parties manipulate district boundaries

Gerrymandering generally works in two ways.

One is called “packing”. This involves placing a large number of opposition voters into a small number of districts. The opposition may win those districts comfortably, but its voters have less influence in surrounding areas.

The other is “cracking”. Here, opposition voters are divided between several districts. They may form a sizeable voting bloc across the state, but not a majority in any individual district.

Both methods can help a party win more seats than its share of the total vote might suggest.

Why the 2026 election is different

The present redistricting battle is unusual because it is happening in the middle of the decade and has a clear partisan purpose.

A recent analysis by Harvard researcher Kosuke Imai found that both Republicans and Democrats have benefited from partisan redistricting in different states. At the national level, the gains largely offset each other.

But the bigger effect is on competition. The research found that the number of highly competitive districts has fallen as voters have become more politically divided by geography. Democrats are increasingly concentrated in cities, while Republicans are stronger in rural areas. This makes it easier to create districts that are safely controlled by one party.

Texas set off the latest map war

Texas Republicans redrew the state’s congressional map in 2025 after President Donald Trump urged the party to pursue additional House seats.

The new map was expected to improve Republican prospects in several districts and could help the party gain as many as five seats. Civil rights groups challenged it, arguing that the boundaries diluted the influence of Black and Hispanic voters.

A lower court initially blocked the map. The US Supreme Court later allowed Texas to use it for the 2026 election.

The case also highlights the difference between partisan and racial gerrymandering. Federal courts have generally been reluctant to decide whether a map is unfairly tilted towards one political party. However, maps can be challenged if race was used unlawfully to weaken minority voters or if the Voting Rights Act was violated.

California launches a counterattack

Democratic leaders in California have responded to Republican-led redistricting efforts elsewhere.

California voters approved Proposition 50, which temporarily gave the state legislature control over congressional map-making. The move was framed as a response to the Texas map and could improve Democratic chances in several House districts.

Republicans have challenged the California plan, arguing that it gives Democrats an unfair advantage and improperly uses race in drawing district boundaries.

The dispute has created a cycle of retaliation. Republican states seek more favourable maps, while Democratic states try to counter those gains wherever they have the political authority to do so.

Missouri map remains tied up in court

Missouri has become another important battleground in the redistricting fight.

A Republican-backed map would make a Kansas City-area district more favourable to the GOP and could give the party an additional House seat. But the map has faced challenges in both state and federal courts.

A Missouri court ruled that the map could not be used unless voters approved it. A federal appeals court later backed its use. The Supreme Court is expected to decide which map will apply in the November election.

The dispute shows how redistricting battles can continue right up to an election, creating uncertainty for candidates, voters and election officials.

Can a gerrymandered map guarantee victory?

No. A party can draw districts with a safety margin, but it cannot fully protect its candidates from a major national shift in voter sentiment.

A strong electoral wave can still defeat incumbents in districts that appear safe. However, gerrymandering can reduce the number of seats that are realistically available to the opposition. That means a party may need to win a larger share of the vote to secure a House majority.

Safe districts can also change the behaviour of elected representatives. When the general election is not competitive, candidates may focus more on party activists and primary voters. This can encourage more partisan positions and reduce pressure to appeal to independent voters.

What is at stake?

The central concern is that politicians may end up choosing their voters instead of voters choosing their representatives.

Gerrymandering can affect which party controls the House, whether minority communities can elect preferred candidates and how competitive congressional elections remain.

The immediate question is whether the new maps will help Republicans protect their House majority or whether a strong Democratic wave will overcome those advantages.

The longer-term debate is about who should draw electoral boundaries. Reform advocates argue that independent commissions, rather than elected politicians, should oversee the process.