With the enactment of the Voting Rights Act of 1970, Congress established 18 years of age for federal and state elections. However, in Oregon v. Mitchell, 400 U.S. 112 (1970), the Supreme Court held the act was unconstitutional as applied to the states. In response, a constitutional amendment was proposed to uniformly lower the age in all elections to 18. The amendment was ratified in just a few months and was in effect for the 1972 Presidential elections.
Public sentiment was in favor of the amendment, in part due to the military draft of men age 18 – 26 years old and their service in the Vietnam war.