California's mid-decade map change was backed by Gov. Gavin Newsom and the Democratic Party in response to efforts by Texas and other Republican-led states to redraw their maps -- at President Donald Trump's urging -- in order to give Republicans a better chance at retaining majority control of Congress.

The Supreme Court on Wednesday denied an effort to overturn California’s new voter-passed congressional map, letting the map go into effect for this year’s midterm elections.

In a one-sentence order, the justices turned down a request from a group of California Republicans that would have required the state to continue to use the map in place for the last several federal e...