The earliest trait of the factory system that caused unease among community leaders was the high rate of low education among child laborers. The first effective step toward legislation governing the education of these children was taken in 1836 when the Massachusetts Legislature adopted a law prohibiting the employment of any child under 15 years of age who had received less than three months of schooling. But that did not stop the factories and mills to employ children who haven't received any education at all, because the laws that was passed did not require proof of the child's age when they were employed, so that meant that could fake it.
The length of the workday for children was the next trait of the factory system to be regulated by legislation. By 1853 several states had approved a 10-hour workday for children under 12 years of age. Despite these limits, the number of children in industry increased greatly in the U.S. after the American Civil War, when industrial expansion resulted in unparalleled demand for workers. By the end of the 19th century nearly one-fifth of all the American children between the ages of 10 and 16 were gainfully employed. By 1910, however, as the result of the public-enlightenment activities of various organizations, notably the National Child Labor Committee, the legislatures of several states had enacted restrictive legislation that led to sharp reductions in the number of children employed in industry. Which meant that they had decreased or you can say fired an amount of children working in the factories and mills. 
Despite the reluctance of state legislators to ratify the child-labor amendment, legislative attempts to deal with the problem nationally continued, notably during the administration of President Franklin D. Roosevelt. The National Industrial Recovery Act, passed by Congress in 1933, established a minimum age of 16 for workers in most industries. In hazardous industries a minimum age level of 18 was established. This law contributed to a substantial decrease in the number of young workers, but the Supreme Court ruled the act unconstitutional in 1935. In the next year Congress passed the Walsh-Healey Act, which prohibits firms producing goods under federal government contract from employing boys and girls under 16 years of age.
The next important legislation on the problem was the Fair Labor Standards Act of 1938, better known as the Federal Wage and Hour Law. This act was declared constitutional in 1941 by the Supreme Court, which thereby overruled its former child-labor decision under a more liberal interpretation of the commerce clause of the Constitution (Article I, Section 8). The Fair Labor Standards Act, amended in 1949, applies to all workers engaged in interstate or foreign commerce. Under the child-labor provisions of the act, minors 16 years of age and over may be employed in any occupation that has not been judged hazardous by the secretary of labor. The minimum age for work in industries classified as hazardous is 18. No minimum age is set for non-hazardous agricultural employment after school hours and during vacation. Minors 14 and 15 years of age may be employed in a variety of non-manufacturing, non-mining, and non-hazardous occupations outside school hours and during vacations for limited hours and under other specified conditions of work.
Every state today has child-labor laws. In most states employment of minors under 16 in factories and during school hours is prohibited. Other provisions include a 40-hour workweek, prohibition of night work, and work permits for minors under 18. Children working on farms are not completely protected by federal and state laws, which make no provisions for nonhazardous farm work outside school hours. The children of migratory workers, who move from harvest to harvest across the United States, are usually not subject to state laws because they do not fulfill residency requirements, and they are often unable to attend local schools, which have no provisions for seasonal increases in school enrollment. Other children exempted from federal and state labor laws are children employed as actors and performers in radio, television, and motion pictures, as newspaper deliverers and sales personnel, or as part-time workers at home.