The American Federation of Labor (AFL) is one of the first federations of labor unions in the United States.

It is founded in Columbus, Ohio in December 1886 by an alliance of craft unions disaffected from the Knights of Labor, a national labor association.

Samuel Gompers of the Cigar Makers' International Union is elected president of the Federation at its founding convention and is reelected every year except one until his death in 1924.The AFL is the largest union grouping in the United States for the first half of the 20th century, even after the creation of the Congress of Industrial Organizations (CIO) by unions that were expelled by the AFL in 1935 over its opposition to industrial unionism.

While the Federation was founded and dominated by craft unions throughout the first fifty years of its existence, many of its craft union affiliates turned to organizing on an industrial union basis to meet the challenge from the CIO in the 1940s.In 1955, the AFL merges with its longtime rival, the Congress of Industrial Organizations, to form the AFL-CIO, a federation which remains in place to this day.

Together with its offspring, the AFL has comprised the longest lasting and most influential labor federation in the United States.