The Child Labor Amendment was submitted to the states for ratification in June 1924. Arizona’s legislature ratified the Amendment in January 1925, making Arizona the second of twenty-eight states to do so. I can’t find the precise date of Arizona’s ratification, but AZ Secretary of State James Kerby certified the legislature’s ratification on January 29. Here’s that certification (now among the records of Congress):

(Thanks to fellow intern Johanna Schein for showing me this document. She knows much more about the politics of child-labor legislation and the origins of the Child Labor Amendment than I do.)

Why the need for a constitutional amendment? In 1916, Congress passed the Keating-Owen Act, which flatly prohibited the interstate shipment of goods made by children under age fourteen and those between fourteen and sixteen who worked more than eight hours a day or forty hours a week. The Supreme Court ruled Keating-Owen unconstitutional in Hammer v. Dagenhart (1918)—there was nothing inherently troublesome about the goods, and “the production of articles, intended for interstate commerce, is a matter of local regulation.” So Congress instead imposed a ten-percent excise tax on persons or establishments employing children under the conditions mentioned in Keating-Owen (1919’s Child Labor Tax Law). The Taft Court struck down this legislative workaround in Bailey v. Drexel Furniture Co. (1922): “To give such magic to the word ‘tax’ would be to break down all constitutional limitations of the powers of Congress and completely wipe out the sovereignty of the states.”

With the Court unwilling to allow Congress to regulate the means of producing goods intended for interstate commerce, the only remaining hope for a national solution to the problem was a constitutional amendment expressly empowering Congress to regulate child labor. Such an amendment was adopted by the House on April 26, 1924 and the Senate on June 2 of that year. The Amendment’s text read as follows:

Section 1. The Congress shall have power to limit, regulate, and prohibit the labor of persons under eighteen years of age.
Section 2. The power of the several States is unimpaired by this article except that the operation of State laws shall be suspended to the extent necessary to give effect to legislation enacted by the Congress.

Widespread acceptance of the Twenty-Seventh Amendment‘s legitimacy (though some scholars style it the “purported” or “so-called” Twenty-Seventh Amendment) has apparently established that dormant amendments with an insufficient number of state ratifications can be reawakened generations later without re-proposal by Congress. Despite major theoretical problems with this view, most famously summarized in the Prohibition-Era case of Dillon v. Gloss (1921), the Child Labor Amendment would become the Twenty-Eighth Amendment to the Constitution if only ten more state legislatures could be persuaded to ratify it. The proslavery Corwin Amendment is also still pending, for that matter.