Which amendment lowered the minimum voting age in the United States to 18?

The Twenty-sixth Amendment lowered the minimum voting age in the United States to 18.

Congress proposed the amendment on March 23, 1971, and the states completed ratification by June 30, 1971. It established a nationally standardized minimum voting age of 18 for state and federal elections.

Support for lowering the voting age grew during the 1960s. A central argument was that citizens old enough to be drafted into military service should also be able to vote. The Vietnam War made that argument especially prominent, although the movement also reflected broader youth activism.

The amendment was adopted unusually quickly, taking only about three months from congressional proposal to ratification. The Supreme Court had previously addressed voting-age rules in Oregon v. Mitchell, but the constitutional amendment provided a nationwide solution rather than leaving different standards for federal and state elections.