During the great surge of industrial growth between 1865 and 1900, the work force expanded enormously, especially in the heavy industries. But the new workers suffered in times of economic depression. Strikes, sometimes accompanied by violence, became commonplace. Legislatures in many states passed new conspiracy laws aimed at suppressing labor.

In response, workers formed organizations with national scope. The Knights of Labor grew to a membership of 150,000 in the 1880s, then collapsed quickly when newspapers portrayed the Knights as dangerous radicals. More enduring was the American Federation of Labor (AFL), founded in 1886 by Samuel Gompers, a leader of the Cigarmakers Union. Comprising craft unions and their members, the AFL had swollen to 1.75 million members by 1904, making it the nation's dominant labor organization.
 

At a time when many workers in Europe were joining revolutionary unions that called for the abolition of capitalism, most American workers followed the lead of Gompers, who sought to give workers a greater share in the wealth they helped produce. A radical alternative was offered by the Industrial Workers of the World (IWW), a union started in 1905 by representatives of 43 groups that opposed the AFL's policies. The IWW demanded the overthrow of capitalism through strikes, boycotts, and sabotage. It opposed U.S. participation in World War I and sought to tie up U.S. copper production during the war. After reaching a peak of 100,000 members in 1912, the IWW had almost disappeared by 1925, because of federal prosecutions of its leaders and a national sentiment against radicalism during and after World War I.
 

In the early 1900s, an alliance formed between the AFL and representatives of the American Progressive Movement (see chapter 3). Together they campaigned for state and federal laws to aid labor. Their efforts resulted in the passage of state laws prohibiting child labor, limiting the number of hours women could work, and establishing workers' compensation programs for people who were injured on the job. At the federal level, Congress passed laws to protect children, railroad workers, and seamen, and established the Department of Labor in the president's cabinet. During World War I labor unions made great strides, and by January of 1919, the AFL had more than 3 million members.