The 1900 census revealed that approximately 2 million children were working in mills, mines, fields, factories, stores, and on city streets across the United States. The census report helped spark a national movement to end child labor in the United States. In 1908, the National Child Labor Committee hired Lewis Hine as its staff photographer and sent him across the country to photograph and report on child labor (see Hine photo). Social reformers began to condemn child labor because of its detrimental effect on the health and welfare of children. Among those helping to incite public opinion against it were Karl Marx and Charles Dickens, who had worked at a factory himself at age 12. One of the most effective attacks came from Dickens's novel Oliver Twist, which was widely read in Britain and the United States. Dickens’s masterwork portrays an orphan boy, raised in poorhouses and workhouses and by street criminals in industrialized London in the 1850s.

The first child labor bill, the Keating-Owen bill of 1916, was based on Senator Albert J. Beveridge's proposal from 1906 and used the government's ability to regulate interstate commerce to regulate child labor. The act banned the sale of products from any factory, shop, or cannery that employed children under the age of 14, from any mine that employed children under the age of 16, and from any facility that had children under the age of 16 work at night or for more than 8 hours during the day. Although the Keating-Owen Act was passed by Congress and signed into law by President Woodrow Wilson, the Supreme Court ruled that it was unconstitutional in Hammer v. Dagenhart 247 U.S. 251 (1918) because it overstepped the purpose of the government's powers to regulate interstate commerce.  In its opinion the Court delineated between the Congress's power to regulate production and commerce.   A second child labor bill was passed in December of 1918 as part of the Revenue Act of 1919 (also called the Child Labor Tax Law). It also took an indirect route to regulate child labor, this time by using the government's power to levy taxes. It  too, was soon found to be unconstitutional in Bailey v. Drexel Furniture Company 259 U.S. 20 (1922). The Court reasoned that “The power of Congress to regulate interstate commerce does not extend to curbing the power of the states to regulate local trade.”

Despite the nation's apparent desire for federal laws against child labor, the Supreme Court's rulings left little room for federal legislation. A constitutional amendment was soon proposed to give Congress the power to regulate child labor. The campaign for ratification of the Child Labor Amendment was stalled in the 1920s by an effective campaign to discredit it. Opponents' charges ranged from traditional states' rights arguments against increases in the power of the Federal Government to accusations that the amendment was a communist-inspired plot to subvert the Constitution. Federal protection of children would not be obtained until passage of the Fair Labor Standards Act in 1938, which was also challenged before the Supreme Court. This time, the movement to end child labor was victorious. In February of 1941, the Supreme Court reversed its opinion in Hammer v. Dagenhart and, in U. S. v. Darby (1941), upheld the constitutionality of the Fair Labor Standards Act. It is still in force today.