Most states have a method for any eligible voter to cast a ballot before Election Day, either during the early voting period or by requesting an absentee ballot. In 11 states, early voting is not available and an excuse is required to request an absentee ballot.
States can choose to provide three ways for voters to cast a ballot before Election Day:
1) Early Voting: In 39 states (including 3 that mail ballots to all voters) and the District of Columbia, any qualified voter may cast a ballot in person during a designated period prior to Election Day. No excuse or justification is required.
2) Absentee Voting: All states will mail an absentee ballot to certain voters who request one. The voter may return the ballot by mail or in person. In 19 states, an excuse is required, while 28 states and the District of Columbia permit any qualified voter to vote absentee without offering an excuse. Some states offer a permanent absentee ballot list: once a voter asks to be added to the list, s/he will automatically receive an absentee ballot for all future elections.
3) Mail Voting: A ballot is automatically mailed to every eligible voter (no request or application is necessary). In-person voting sites may also be available for voters who would like to vote in-person and to provide additional services to voters. Three states (Oregon, Washington, and Colorado) mail ballots to all eligible voters for every election. Other states may provide this option for some types of elections.
In Tennessee there are two ways in which a registered voter may cast a ballot before the actual election day: in-person early voting (open to all registered voters) and absentee, or "by-mail" voting (must meet certain requirements).
In Virginia an excuse is required for absentee voting and early in-person voting is not offered.
Source: National Conference of State Legislatures