vote.gov - register to vote. An official website of the United States government
usa.gov - visit your state's election office website for state-wide voting guidance.
"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. - US Constitution stated in Amendment XXVI, which was ratified by the states in 1971