Texas Republicans’ transfer to redraw their congressional map mid-decade and Democrats’ retaliatory redistricting efforts have captured nationwide consideration for a quite simple cause: How Home districts are drawn can form American politics for years.
Gerrymandering usually reduces the variety of aggressive races, and it could possibly lock in almost immovable benefits for one get together or one other. Beneath the brand new map proposed in Texas, no seat’s presidential vote would have been determined by single digits in 2024, and Republicans would have a path to pad their slim congressional majority within the 2026 midterm elections. This implies extra individuals may reside in congressional districts below stable management of 1 get together.
NBC Information analyzed how the query of who attracts the maps — and the way they do it — can form elections for years afterward.
The distinction between protected seats and aggressive districts
Who attracts district strains could make the distinction between contested normal elections in a state in November and elections which might be barely greater than formalities.
NBC Information analyzed each Home race within the nation from 2012 to 2020, the final full 10-year redistricting cycle, based mostly on how every district was drawn. In states the place state legislators drew the maps, single-digit races (elections through which the winners received by lower than 10 proportion factors) had been rarest. Solely 10.7% of Home races fell into that aggressive class.
There are many causes that do not contain gerrymandering. For one factor, voters of each events have more and more clustered lately, leaving fewer locations across the nation which might be politically divided.
Nonetheless, gerrymandering does play a big position. When commissions or state or federal courts drew the strains final decade, the speed of aggressive elections jumped, although protected seats are nonetheless overwhelmingly doubtless. Aggressive elections had been particularly prevalent in states with court-drawn districts: 18.1% of races in these states had single-digit margins from 2012 via 2020.
A take a look at Pennsylvania, whose legislative-drawn map was thrown out and changed in 2018 by the state Supreme Courtroom, illustrates the dramatic change that may come based mostly on who attracts congressional strains. The identical state with the identical voters dwelling in the identical locations all of the sudden had many extra aggressive elections.
From 2012 via 2016, simply three of Pennsylvania’s 54 Home normal elections below the preliminary map had single-digit margins.
After the state Supreme Courtroom threw out the map and imposed a brand new one, the variety of battleground races bumped up. Eight of 36 Home races had single-digit margins in 2018 and 2020.
In the meantime, forward of the 2026 midterms, The Prepare dinner Political Report with Amy Walter charges 40 Home districts as toss-ups or barely leaning towards one get together. Greater than half (23) of these 40 aggressive districts are in states the place commissions or courts drew the maps.
How a state’s partisanship compares with whom it sends to Congress
The facility of the redistricting course of can bend a state’s illustration in Congress away from its general partisanship, with broad variations between the statewide vote in some states and the make-up of their Home delegations.
Take Illinois, for instance, the place Donald Trump acquired 44% of the vote in 2024. Republicans maintain solely three of the state’s 17 seats in Congress, or 18%. (NBC Information is presidential information as a substitute of Home information right here as a result of some races are uncontested.) And although Trump acquired 38% of the vote in California final 12 months, Republicans maintain solely 17% — that’s 9 seats — of the state’s 52 congressional districts.
On the opposite aspect of the ledger, Trump acquired 58% help in South Carolina final 12 months, and 86% of the state’s Home delegation is Republican. In North Carolina, 51% voted for Trump final 12 months, and Republicans have 71% of the delegation.
The comparability between Home seats and presidential election efficiency isn’t excellent. Nevertheless it demonstrates that how district strains are drawn can generate totally different outcomes from what statewide outcomes would possibly recommend.
Proper in the course of the chart is Virginia. Its 11 congressional districts cut up 6-5 for Democrats, that means Republicans maintain almost 46% of the state’s seats in Congress, and Trump received 46% of the vote in Virginia final 12 months.
Additionally, simply because a state’s maps favor one get together in contrast with the statewide outcomes after one election doesn’t imply the redistricting course of was biased. Tightly divided Pennsylvania has seven Democrats and 10 Republicans in Congress, and three GOP-held districts are rated as toss-up or lean-Republican races in 2026, based on the Prepare dinner Political Report.
Every state charts its personal course
Since every state is liable for dealing with its personal redistricting, the method is totally different relying on the place you look, giving immense energy to totally different establishments state by state.
In 27 states, legislatures accredited the maps. In seven, impartial commissions accredited them, seven had court-approved maps, two had political commissions, and one state’s maps had been accredited by a backup fee, based on information from Loyola Legislation College. (The six states that elect just one particular person to the Home don’t draw new congressional maps.)
Loyola Legislation College’s “All About Redistricting” web site defines politician commissions as panels elected officers can serve on as members. The web site defines backup commissions as backup procedures if legislatures can’t agree on new strains.
Some impartial redistricting commissions aren’t as highly effective as these in different states. New York has an impartial fee, however the Legislature overrode its map and handed its personal in 2024.
