Twenty-Sixth Amendment, Section 1:
The right of citizens of the United States, who are eighteen years of age or older, to vote shall not be denied or abridged by the United States or by any State on account of age.
In extending the Voting Rights Act of 1965 in 1970, 1 Congress included a provision lowering the age qualification to vote in all elections, federal, state, and local, to 18. 2 In a divided decision, the Supreme Court held that Congress was empowered to lower the age qualification in federal elections, but voided the application of the provision in all other elections as beyond congressional power. 3 Confronted thus with the possibility that they might have to maintain two sets of registration books and go to the expense of running separate election systems for federal elections and for all other elections, the states were receptive to the proposing of an Amendment by Congress to establish a minimum age qualification at 18 for all elections, and ratified it promptly. 4