Answer:
Although throughout labor union history, and the struggle of American workers to gain better conditions, better wages, and be allowed to unionize to champion their causes, there have been several strikes and events that in one way, or the other, have influenced the development of the labor union movement, and cause, according to sources such as the AFL-CIO, there are two that were major turnabouts for the movement, and in some way, forced a change in labor policies in the United States.
The first one is known as The 1892 Homestead Strike, in Pennsylvania. This strike was really violent, and it changed U.S history permanently, and it forced real changes in labor union laws. In essence, it became a fight between the steel workers union, the Amalgamated Association of Iron and Steel Workers in Homestead, one of the many plants of Andrew Carnegie, and the management of the plant. The outcome was a bloody one, especially on the workers side.
The second one is the McKees Rock Strike in 1909. According to labor union historians and activists, such as Eugene V. Debs, this strike, which was the first time that immigrant workers rose up to demand better conditions, changed the entire way the union labor movement proceeded from then onwards. It was caused in the Pressed Steel Car Co. plant, in McKees Rock, when the workers of the plant, most of them immigrants from Europe, started demanding better opportunities, better payment and conditions.
