In 1971, the Twenty-sixth Amendment set the legal voting age at 18 for both US federal and state elections. In the United States nineteen states permit 17-year-olds to vote in primary elections and caucuses if they will be 18 years of age, by election day.
http://www.answers.com/Q/What_is_the_voting_age_in_the_US
A voting age is a minimum age established by law that a person must attain to be eligible to vote in a public election. Typically, the age is set at 18 years; however, ages as low as 16 and as high as 21 exist (see list below).
https://en.wikipedia.org/wiki/Voting_age
The 26th Amendment, ratified in 1971, establishes 18 as the minimum voting age for both state and federal elections.
http://www.nytimes.com/roomfordebate/2012/05/28/do-we-need-to-redefine-adulthood/leave-the-voting-age-alone
[3]. Arguments that influenced the decision of The Electoral Commission to recommend maintaining the minimum voting age at 18 included: 1  International comparisons-most countries have a minimum voting age of 18 and a pattern of harmonised voting and candidacy ages prevails across Europe and Commonwealth countries.
http://www.electoralcommission.org.uk/i-am-a/journalist/electoral-commission-media-centre/news-releases-reviews-and-research/voting-age-should-stay-at-18-says-the-electoral-commission
Arguments that influenced the decision of The Electoral Commission to recommend maintaining the minimum voting age at 18 included: 1  International comparisons-most countries have a minimum voting age of 18 and a pattern of harmonised voting and candidacy ages prevails across Europe and Commonwealth countries.
http://www.electoralcommission.org.uk/i-am-a/journalist/electoral-commission-media-centre/news-releases-reviews-and-research/voting-age-should-stay-at-18-says-the-electoral-commission
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. Section 2. The Congress shall have the power to enforce this article by appropriate legislation.
https://en.wikipedia.org/wiki/Twenty-sixth_Amendment_to_the_United_States_Constitution
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. Section 2. The Congress shall have the power to enforce this article by appropriate legislation.
https://en.wikipedia.org/wiki/Twenty-sixth_Amendment_to_the_United_States_Constitution
The debate about lowering voting age from 21 to 18 in the U.S. began during World War II and intensified during the Vietnam War. In the 1970 case Oregon v. Mitchell the Supreme Court ruled that Congress had the right to regulate the minimum age in federal elections; however, not at local and state level.
https://en.wikipedia.org/wiki/Voting_age
The following year, when Congress passed a bill extending and amending the Voting Rights Act of 1965, it contained a provision that lowered the voting age to 18 in federal, state and local elections.
http://www.history.com/topics/the-26th-amendment
Subsequently, Oregon and Texas challenged the law in court, and the case came before the Supreme Court in 1970 as Oregon v. Mitchell. By this time, four states had a minimum voting age below 21 including Georgia, Kentucky, Alaska and Hawaii.
https://en.wikipedia.org/wiki/Twenty-sixth_Amendment_to_the_United_States_Constitution
minumum age to vote
The minimum age to vote is 18. The minimum age to vote is 18 years.