Final answer:
Labor unions have significantly contributed to improving working conditions, with the United Mineworkers union in the 1950s and 1960s serving as an example of demanding labor-saving machinery to increase productivity and wages. They also sought better work hours, safety, and health benefits but still faced challenges with representation at the end of the nineteenth century.
Step-by-step explanation:
Labor unions have been historically significant in improving working conditions for workers by employing strategies such as collective bargaining and strikes. One notable example is the action taken by the United Mineworkers union during the 1950s and 1960s.
This union demanded the installation of labor-saving machinery in mines, knowing that although this would eventually reduce the number of jobs due to mechanization, it would lead to a necessary increase in worker productivity and subsequently higher wages.
Beyond higher wages, unions have fought for parameters around work hours, safety standards, ending child labor, and negotiating health benefits. Over the decades, despite facing setbacks and public opinion challenges, labor unions like the National Labor Union, Knights of Labor, and the American Federation of Labor have grown in number, squarely positioning themselves as defenders of worker's rights.
However, it's important to note that at the end of the nineteenth century, the majority of American laborers were still unrepresented by unions, illustrating the ongoing struggle between labor and factory ownership that continued into the twentieth century.