Labor history of the United States
From dKosopedia
History of Unionism in the USA
The first major effort to organize workers' groups on a nationwide basis appeared with The Noble Order of the Knights of Labor in 1869. The Knights of Labor organized workers by industry.
In 1886 the American Federation of Labor (AFL) was founded, which sought to organize skilled workers by craft, not by industry. Many skilled workers left the Knights of Labor for the more conservative AFL.
In 1905 the Industrial Workers of the World (IWW) was founded as an industrial union, i.e. one that organized workers by industry, not by craft. It sought to organize all workers into "one big union" which who solve such things as jurisdictional problems, as well as bring all workers together. The US government went after the IWW during and after World War I, jailing and killing its "leaders" and members. The organization has yet to recover from this in terms of numbers and influence.
The Congress of Industrial Organizations (CIO) was originally founded as the Committee of Industrial Organizations within the AFL in 1935, at a conference where UMWA head John L. Lewis famously punched Carpenters head William Hutcheson. The CIO sought to organize workers by industry, not by craft. The CIO split from the AFL in 1938. In 1948, the CIO expelled its left-led unions.
In 1955 the AFL and CIO merged and became the AFL-CIO.
Over the past decades, the number of unionized workers in the United States has dropped dramatically, especially in non-government jobs. In the 1950's, over one third of American workers were unionized. In 2003, only 8.2% of non-government jobs were unionized, and the number has been declining every year.