<P> Unions began forming in the mid-19th century in response to the social and economic impact of the industrial revolution . National labor unions began to form in the post-Civil War Era . The Knights of Labor emerged as a major force in the late 1880s, but it collapsed because of poor organization, lack of effective leadership, disagreement over goals, and strong opposition from employers and government forces . </P> <P> The American Federation of Labor, founded in 1886 and led by Samuel Gompers until his death in 1924, proved much more durable . It arose as a loose coalition of various local unions . It helped coordinate and support strikes and eventually became a major player in national politics, usually on the side of the Democrats . </P> <P> American labor unions benefited greatly from the New Deal policies of Franklin Delano Roosevelt in the 1930s . The Wagner Act, in particular, legally protected the right of unions to organize . Unions from this point developed increasingly closer ties to the Democratic Party, and are considered a backbone element of the New Deal Coalition . </P> <P> Pro-business conservatives gained control of Congress in 1946, and in 1947 passed the Taft - Hartley Act, drafted by Senator Robert A. Taft . President Truman vetoed it but the Conservative coalition overrode the veto . The veto override had considerable Democratic support, including 106 out of 177 Democrats in the House, and 20 out of 42 Democrats in the Senate . The law, which is still in effect, banned union contributions to political candidates, restricted the power of unions to call strikes that "threatened national security," and forced the expulsion of Communist union leaders (the Supreme Court found the anti-communist provision to be unconstitutional, and it is no longer in force). The unions campaigned vigorously for years to repeal the law but failed . During the late 1950s, the Landrum Griffin Act of 1959 passed in the wake of Congressional investigations of corruption and undemocratic internal politics in the Teamsters and other unions . </P>

When did labor unions begin to gain some legal rights in the united states