Dr. Leslie B. McLemore remembers the fear that simmered in the air as he went door to door as a young college student working to register Black voters in rural Mississippi in the early 1960s. The threats. The gun brandished in his face by a patrol officer along a highway.

It made the celebration even more joyful as he joined other students crowding around a television when the Voting Rights Act became law in 1965. On Wednesday, he grappled with different emotions after the Supreme Court dealt it its latest blow.

“I just never in my wildest imagination ever dreamed that we would be, in 2026, where we are now, based on what happened in 1965,” said Dr. McLemore, 85, one of the few surviving veterans of the civil rights movement. “It’s a historic, sad day.”

Given the Supreme Court’s conservative majority and other rulings that had chipped away at the Voting Rights Act over the years, Wednesday’s decision did not entirely surprise voting rights groups or Black leaders across the South, where the landmark law has led states to create several majority-Black voting districts.

But Justice Samuel A. Alito Jr., in writing for the majority, took some aback with his assertion that the nation had undergone “vast social change” since the law’s passage. He pointed in part to increased voter registration and turnout by minorities.

“Discrimination that occurred some time ago, as well as present-day disparities that are characterized as the ongoing ‘effects of societal discrimination,’ are entitled to much less weight,” he wrote.

The ruling was cheered by conservatives across the country, many of whom had objected to the law’s focus on race. The path forward, said Amir Hassan, a Black Republican running for Congress in Michigan, is for people to align themselves ideologically, rather than by “who has melanin and who doesn’t have melanin.”

“It’s upsetting, the fact that people think I want the same thing as another person just because of our skin tone,” said Mr. Hassan, who is running in a district where most voters are white.

Black Americans, especially in the South, have historically backed Democrats. So if the ruling leads G.O.P.-led state legislatures to eliminate majority-minority congressional districts, dividing those voters among Republican-safe districts, the political ripples will be significant.

For some Black Southerners, the Supreme Court’s reasoning amounted to a debatable assessment of racial progress.

“He can write those words,” said Dr. McLemore, who pledged to keep talking about the struggles that civil rights veterans had endured to secure passage of the Voting Rights Act. “But he has no idea and no appreciation for what Black people and what people of color have gone through in this country.”

The gains in Black representation across the country since the act passed have been particularly meaningful in the South.

As recently as 2024, Alabama and Louisiana each sent two Black representatives to Congress — the result of litigation over new congressional maps. At least one of those seats — in Louisiana’s Sixth Congressional District — is now in jeopardy, given that a majority of the Supreme Court found the new map to be an illegal racial gerrymander.

“I’m somewhat depressed about the ruling. No way is it better,” said Delores Suel, 77, who is Black and owns a child-care center in Jackson, Miss., part of the state’s lone majority-Black district. “The Supreme Court missed the mark.”

Elsewhere in Jackson, Tyra Dean, 55, who is Black and owns a taxi company, said that “discrimination still exists.”

“I feel what they are doing now will lead to more discrimination,” she continued.

The suggestion that the standing of Black voters in the South had improved enough to warrant changing the framework courts use to assess compliance with the Voting Rights Act rankled some Black elected Democrats.

“I want to be crystal clear — that is not the experience that most people of color have in the South, whether we’re talking about politics, education, housing, access to health care or the professional world,” said Raumesh Akbari, a Democratic state senator in Tennessee and the chamber’s minority leader.

For some national civil rights leaders who watched what they describe as the rise and fall of the Voting Rights Act over time, Wednesday’s decision felt like an abrupt end to decades of political progress.

“The majority opinion is illogical when racially polarized voting in the South is real; when the racial wealth gap, the educational achievement gap and health outcome gaps are real; when discrimination claims in employment are still rampant,” said Marc Morial, president of the National Urban League.

Press Robinson, an activist in Baton Rouge, La., who was involved in challenging past congressional maps, said he feared the ruling could have ramifications not just for the makeup of Congress, but for all levels of government.

“Judges, school board members, councilmen — doesn’t matter, it will affect them all,” he told reporters in a news conference on Wednesday.

Mr. Robinson, who grew up in South Carolina during segregation, predicted that the Republicans who control the government in Louisiana — and in nearly every other Southern state — would move aggressively to reshape the political landscape from the local level on up, wiping out Black representation.

“They are determined to see to it that we don’t have a voice at all,” he said.

Reporting was contributed by Michelle Baruchman, Jimmie E. Gates, Clyde McGrady, Bryant K. Oden and Rick Rojas.