Sometimes called a form of American holocaust, lynchings were effective as a kind of homegrown terrorism to keep intact the social structure that preceded the Civil War. They were driven by fear among whites as much as hatred of blacks. But dozens of postcard images of lynching gangs - and a body count kept by the Tuskegee Institute - were also responsible for changing attitudes about race, culminating in the civil rights movement and the ebbing not only of mob violence, but of separate water fountains.
Yet the changes took time. Between 1880 and 1960, 200 anti-lynching bills were introduced, and seven presidents urged their passing. Filibustering Southern senators scuttled the vote every time, saying a lack of law enforcement in the tumultuous postwar South necessitated mob justice.
Critics today say Congress's failure surely fueled the boldness of the mob. Acknowledging that role is a step forward, many say. The Senate's official apology, approved Monday, is one of only a handful it has issued throughout history.
"The Senate failed these Americans," said Sen. Mary Landrieu (D) of Louisiana, who sponsored the action after the Committee for Public Apology began pressing the issue in 2003.
The move is likely to help focus debate in a country still struggling with the aftermath of slavery.
"America's racial experience is like a death in the family: The first thing that happens in the process is denial, then anger, then grief, and, finally, healing," says Mr. Akers. "And we've still got parts of the country in denial, some that are angry, some that are grieving, and some that have looked the beast firmly in the eye and experienced the healing."
Still, in all the emotionalism over the apology, some worry that it will just divert attention from the living legacies of racism. "I'm suspicious of government apologies," says Jonathan Markovitz, a sociologist and author of "Legacies of Lynching." "There's a way where you can pay attention to something and empty it of meaning. What defined lynching is it was a method of terrorism that worked to preserve racial stratification, and in many ways those structures of inequality are still in place."