Under the U.S. Constitution the guarantees right to hold elections, but the method and place are left to the states, with Congress having the power to alter their regulations. Political candidates are usually chosen by delegate convention, direct primary, nonpartisan primaries, or petition. The candidate who receives the most votes is usually elected, but an absolute majority may be required. Corruption in elections has been reduced over time by corrupt practices acts, poll watching, the institution of primary elections, and the introduction of voting machines. All states have residency requirements for voting. The National Voter Registration Act of 1993 was designed to reverse declining voter registrations by permitting registration at motor vehicle departments and other agencies. Certain classes of felons and some others are deprived of the vote.
Constitutional amendments have expanded voting rights over the course of time. The Seventeenth Amendment (1913) provided for popular election of senators. The Fourteenth Amendment (1868) and Fifteenth Amendment (1870) were designed to forbid the disenfranchisement of African-American men after the Civil War, and the Nineteenth (1920) conferred the vote on women. The Twenty-third Amendment (1961) permitted residents of the District of Columbia to vote in the presidential elections, while the Twenty-fourth Amendment (1964) outlawed payment of poll or other taxes as a condition for voting. The Twenty-sixth Amendment (1971) lowered the voting age from 21 to 18.
