“There’s much more that could be done in terms of our curriculum to make sure that folks understood the full scope of anti-black violence in American history,” Dr. Hobbs said. “I think if they understood that, perhaps they would understand the Black Lives Matter movement as an extension of centuries, really, of advocacy on the part of African-Americans.”

Researchers with the Equal Justice Initiative, a nonprofit legal advocacy group, have documented more than 4,000 lynchings in the United States between 1877 and 1950, mostly — though not exclusively — in the South. The extrajudicial killings were instruments of terror, often conducted as public spectacles in full view of, or with cooperation from, law enforcement.

Bryan Stevenson, a civil rights lawyer and the executive director of the Equal Justice Initiative, said that the terror drove millions of black people to flee the South, drastically altering the demographic geography of the United States.

“I think it’s important that there is an effort now to acknowledge this history and to do what we should have done a century ago,” he said. “A lot of folks will say, ‘Well, it’s not relevant today; it’s not necessary today.’ But lynching violence was created by politics of fear and anger, and we should never assume that an era of fear and anger will never occur again.”

The bill that the Senate approved last year noted that 99 percent of lynching perpetrators escaped punishment.

Black activists, writers and speakers risked their lives by calling attention to the violence. In 1892, the journalist Ida B. Wells, who fought fiercely to end lynching, wrote that “the strong arm of the law must be brought to bear upon lynchers in severe punishment, but this cannot and will not be done unless a healthy public sentiment demands and sustains such action.”