The American Federation of Labor (AFL) was one of the first and largest federations of labor unions in the United States. In 1955, the AFL merged with the Congress of Industrial Organizations (CIO) to create the AFL-CIO, which now represents around 12.5 million Americans.

Many early members of the AFL were former members of the Knights of Labor, the largest and most influential American union organization during the 1870s. Unlike the Knights of Labor, the AFL sought to stay out of the political arena and encouraged peaceful negotiations, sanctioning strikes only as a last resort to resolve disputes. In the 1800s, the AFL actively discriminated against African-Americans and other visible minorities, unskilled workers and women by refusing to admit them to the federation. By 1920, the AFL represented over four million workers, but came under pressure during the next two decades to become more inclusive and allow formerly excluded people to join.

"To bring social and economic justice to our nation by enabling working people to have a voice on the job, in government, in a changing global economy and in their communities."

• JFK Library: Remarks of Senator John F. Kennedy to the American Federation of Labor National Legislative Council on Tuesday, February 16, 1954 - John F. Kennedy Presidential Library & Museum