During the late 1800s the use of child labor in US factories was most opposed by...?

During the late 1800s, the use of child labor in US factories was most opposed by labor unions, progressive reformers, and social activists. These groups highlighted the harsh working conditions, long hours, and minimal pay that children endured, advocating for reforms to protect young workers. Organizations like the National Child Labor Committee emerged, pushing for legislation to limit child labor and improve educational opportunities. Their efforts eventually contributed to the establishment of laws regulating child labor in the early 20th century.