When an assassin shot and killed Martin Luther King Jr. in Memphis in 1968, the civil rights icon was in town supporting black sanitation workers on strike for higher wages and better treatment.

“If I do not stop to help the sanitation workers, what will happen to them?” King said, in an appeal for citizens to support workers, in what would be his final speech. “That’s the question.”

Historically, the organized labor movement has been a force that contributed to the empowerment of African Americans. But the path was not always direct or easy.

During the late 19th and early 20th centuries, African Americans faced discrimination and segregation within labor unions. In response, they started their own, while continuing to seek membership in mainstream unions.

“Participation in unions was important as a type of training ground for black leadership,” said Steven Pitts, an expert on labor issues with the University of California, Berkeley. “You find repeatedly, across the country, blacks who were leaders in unions and also leaders in the community.”

African Americans for decades have achieved rights through labor unions. (© AP Images)

A. Philip Randolph was such a leader. In 1925, Randolph founded the Brotherhood of Sleeping Car Porters, one of the most influential predominantly African-American unions. (The economic status of porters in their communities and the tussles with bosses over unionizing are central themes in the recent play titled Pullman Porter Blues.)

“Handsome, tall, imposing in stature and bearing, and possessed of a magnificent speaking voice,” Randolph proved an adept political strategist. By organizing the March on Washington Movement in 1941 and organizing a potential 100,000-person march on Washington, Randolph persuaded President Franklin D. Roosevelt to end segregation in defense industries.

Years later, another African-American union leader, Edgar Nixon of the Alabama branch of the Brotherhood of Sleeping Car Porters, played a pivotal role in organizing the 1955 Montgomery Bus Boycott.

Pitts observed that as African Americans joined racially mixed unions, those organizations became more likely to push for civil rights issues. Some very powerful desegregated unions supported Edgar Nixon’s efforts to end segregation in Montgomery and beyond.

“Financial support from the UAW [United Auto Workers] and other unions for the Southern Christian Leadership Conference was important in supporting efforts in the South,” Pitts said.

Union membership continues to help African Americans improve their livelihoods. One study concludes that black and African-American union members make 32 percent more than their nonunion counterparts. And African-American workers today belong to unions at a greater rate than that of any other race/ethnic group.