How was child labor addressed during the industrial age?

After the Civil War was the "Rise of Industrial America, 1876 - 1900". A lot of people could barely make ends meat so they had to have their children as young as three years old work which was extremely dangerous and gave little time for education.

Because of those, and many other reasons, Congress had to reform old child labor laws and create new laws. It had to enforce a minimum working age and established maximum hours children could work.