WASHINGTON — The Supreme Court on Thursday ruled that Republicans in South Carolina did not unlawfully consider race when they drew a congressional district in a way that removed thousands of Black voters, making it harder for civil rights plaintiffs to bring racial gerrymandering claims.

The court, divided 6-3 on ideological lines with conservatives in the majority, said civil rights group had not done enough to show that legislators were focused on race in drawing the Charleston-area district currently represented by Rep. Nancy Mace, a Republican.

While the Supreme Court was considering the case, much more slowly than expected, the lower court that had invalidated the map said it could be used for this year’s election.

The justices’ ruling will therefore have no immediate impact in South Carolina, but it sets the rules of the road for future redistricting efforts, making it easier for maps to be drawn that disfavor Black voters as long as the map-makers can show they are using race as a proxy for political affiliation.

In doing so, the court sided with Republican state officials who said their sole goal was to increase the Republican tilt in the district.

As a result of the ruling, Mace’s district will not have to be redrawn, delivering a blow to Democrats who hope to secure a more favorable map. Litigation on a separate claim brought by plaintiffs against the map could continue.

Writing for the majority, conservative Justice Samuel Alito wrote that “no direct evidence” supports the lower court’s finding that race was a key consideration when the map was drawn.

“The circumstantial evidence falls far short of showing that race, not partisan preferences, drove the districting process,” he added.

In dissent, liberal Justice Elena Kagan wrote that the majority had “stacked the deck” against the challengers.

“What a message to send to state legislators and mapmakers about racial gerrymandering,” she added.

The Supreme Court was reviewing a January 2023 lower court ruling that said race was of predominant concern when one of the state’s seven districts was drawn. Republicans led by South Carolina Senate President Thomas Alexander appealed the decision.

Republicans redrew the boundaries after the 2020 census to strengthen GOP control of what had become a competitive district.

Democrat Joe Cunningham won the seat in 2018 and narrowly lost to Mace in 2020. Two years later, with a new map in place, Mace won by a wider margin.

The roughly 30,000 Black voters who were moved out of the district were placed into the district held by Democratic Rep. James Clyburn, who is Black. It is the only one of the seven congressional districts that is held by Democrats.

The NAACP Legal Defense and Educational Fund and other civil rights groups alleged not only that Republicans unlawfully considered race when they drew the maps but that they also diluted the power of Black voters in doing so.

The claims were brought under the Constitution’s 14th Amendment, which requires that the law applies equally to everyone. The case arose under a different legal theory from the major ruling this year in which civil rights advocates successfully challenged Republican-drawn maps in Alabama under the Voting Rights Act.