Eligibility to vote in the U.S. is determined by both federal and state law. Currently, only citizens can vote in U.S. elections.
Absent federal law or constitutional amendment, each state is given considerable discretion to establish qualifications for suffrage and candidacy within their own jurisdiction.
The federal role in elections has increased through amendments and enacted legislation, such as the Voting Rights Act. At least four of the fifteen post-Civil War constitutional amendments were ratified specifically to extend voting rights to different groups of citizens.