Some states and local governments may hold a blanket primary, where party affiliations do not appear on the ballot by the candidates' names. This nonpartisan system is commonly used when electing judges. Qualifications for Voting States require voters to be U.S. citizens. Traditionally voters also had to be at least 21 years old. This was based on an old Anglo-Saxon law that considered people adult at 21.
States also require various periods of residency before voting is permitted.
Until the 1960's, some states required citizens to prove that they could read and write before voting. If an examiner decided a citizen could not read well enough, that citizen was denied the right to vote. In southern states, examiners used these literacy tests unfairly to deny most black people the right to vote. In 1965, Congress passed the Voting Rights Act, which suspended the use of most literacy tests, and several years later the tests were banned permanently. According to the 26th Amendment to the U.S. Constitution, any U.S. citizen age 18 or older may vote.