Mobile people vote less when faced with restrictive registration and residency requirements. All states today require that a voter be 18 years old by election day, a U.S. citizen, and a legal resident of the state. Most states also restrict voting for currently incarcerated felons and for those legally declared mentally incompetent. Historically, many states imposed lengthy residency requirements at the state, county, and local levels, some as long as two years. Until 1970,
Texas required one year residence in the state. States justified lengthy residency requirements with arguments of fraud prevention and a promise of more knowledgeable voters, but often used them simply to disenfranchise. However, the 1970 Voting Rights Act set thirty days as the maximum permissible residency requirement in presidential elections
and a 1972 U.S. Supreme Court decision (Dunn v. Blumstein, 405 U.S. 330) applied the thirty day maximum to state and local elections. Since then most states have reduced or eliminated their residency requirements. Absent any evidence of increased voter fraud, a few states have set aside any residency requirements with Election Day registration.