From Texas to Oregon, competitive congressional districts are disappearing. As states finalize new borders ahead of the 2022 midterms, state legislatures are approving maps they hope will advantage one party in the coming struggle to control the narrowly held U.S. House.

In the 15 states that approved new congressional district maps as of Monday morning, the number of districts where the 2020 presidential margin was within five percentage points has fallen from 23 to just 10, according to a Post analysis. The new maps in those states have already netted a double-digit increase in solidly Republican seats compared with previous maps there. The completion of maps in more states will provide a fuller picture in the coming months.

The maps could face years of legal challenges once they are approved by state legislatures or other commissions charged with drawing the lines. The net effect of the changes in motion is that the next session of Congress will have an even more partisan makeup, and likely more rancor, than the already polarized House today.

Texas

Currently, Republicans hold a 23-to-13 advantage over Democrats in the House delegation. The new lines, which include two additional seats because of population growth, nearly double the safest Republican seats from 11 to 21 and increase the safest Democratic seats from eight to 12. One seat leans Democratic and three lean Republican, according to the analysis.

Ohio

The congressional map in Ohio is already favorable to Republicans — Joe Biden received 45 percent of the vote in 2020, but Democrats currently make up just one-fourth of the state’s congressional delegation — and the new map could intensify that difference. Republicans are expected to have seven solid seats, up from five.

The new map slightly increases the number of seats with close presidential margins, in part maintaining close districts currently held by Republicans, and eliminates a solid Democratic seat along Lake Erie.

Oregon

Though Democrats will draw fewer districts than Republicans nationwide, they are countering with their own favorable maps in states like Oregon, which will gain a new seat from reapportionment. The National Republican Congressional Committee had planned to target the state’s single competitive district and new district as possible Republican gains. But the Democratic-controlled legislature passed a map that sets both those seats up to be safely Democratic seats.

Republican votes have been packed into the state’s single right-leaning eastern district, making the seat even more solidly Republican, while Democratic votes around Portland have been split, lending the party an advantage in four separate districts.

North Carolina

Growth in Democratic-leaning cities and suburbs gave North Carolina a new seat from reapportionment as well, but the maps passed by the Republican-controlled state legislature add new solidly Republican district.

North Carolina’s 1st District, a majority minority and solidly Democratic area in the northeast corner of the state, was redrawn into a much more competitive district. Rep. G.K. Butterfield, who has represented the district since 2004, announced his retirement on Friday, citing the new map he said is “racially gerrymandered.”

“It will disadvantage African American communities all across the 1st Congressional District,” Butterfield said in a video statement. “I am disappointed, terribly disappointed with the Republican majority legislature for again gerrymandering our state’s congressional districts and putting their party politics over the best interests of North Carolinians."