Louisiana Gov. Jeff Landry, a Republican, has signed a bill creating a new congressional map that establishes a second majority-black district—which could cost Republicans a seat in Congress, threatening their slim House majority.
Mr. Landry signed the new map into law on Jan. 22, several days after Louisiana lawmakers approved it in a special legislative session called to comply with a federal court order requiring the state legislature to draw the new map in compliance with the federal Voting Rights Act—or let the courts redraw the boundaries at trial.