Which amendment states that citizens must be 18 years or older to vote?

The 26th Amendment to the United States Constitution specifically addresses the voting age, establishing that citizens must be at least 18 years old to vote in federal, state, and local elections. Ratified in 1971, this amendment was a response to the significant number of young Americans, particularly those serving in the Vietnam War, who were not able to vote. The movement behind this amendment emphasized that if individuals were old enough to fight for their country, they should also have the right to participate in determining its governance through voting. This amendment reinforced the democratic principle of inclusion, ensuring that younger citizens could exercise their rights like their older counterparts.