Similar legislation followed on the European Continent as countries became industrialized. Although most European nations had child labor laws by 1940, the material requirements necessary during World War II brought many children back into the labor market. Legislation concerning child labor in other than industrial pursuits, e.g., in agriculture, has lagged.
In the Eastern and Midwestern United States, child labor became a recognized problem after the Civil War, and in the South after 1910. Congressional child labor laws were declared unconstitutional by the Supreme Court in 1918 and 1922. A constitutional amendment was passed in Congress in 1924 but was not approved by enough states. The First Labor Standards Act of 1938 set a minimum age limit of 18 for occupations designated hazardous, 16 for employment during school hours for companies engaged in interstate commerce, and 14 for employment outside school hours in nonmanufacturing companies. In 1941 The Supreme Court ruled that Congress had the constitutional authority to pass this act.
Nearly all member nations of the International Labor Organization (ILO) regulate the employment of children in industry, and most also regulate commercial work; some nations regulate work in the street trades, while a few control agricultural and household work. Despite such regulation attempts, as many as 26% of all children between the ages of 5 and 14 (an estimated 246 million children) were engaged in economic activity in 2005, with the highest percentage in developing nations in sub-Saharan Africa. Not all such work is considered child labor, but some 186 million children were estimated to be involved in child labor as defined under international agreements. The 1973 ILO Minimum Age Convention, banning any form of child labor, has been ratified by 117 nations. In 1999, ILO members unanimously approved a treaty banning any form of child labor that endangers the safety, health, or morals of children, but the treaty covered such universally objectionable forms of work as slavery, forced labor, child prostitution, criminal activity, and forced military recruitment and could be seen as a step backward from the 1973 treaty. The treaty was also criticized for permitting voluntary enlistment in the military by persons under the age of 18.
See W. Trattner, Crusade for the Children (1970); also annual reports of the National Child Labor Committee.