An elector is a person who is qualified to vote in an election. In the United States, the term "elector" is most commonly used to refer to a member of the Electoral College, which is responsible for electing the President and Vice President of the United States. Each state gets as many electors as it has members of Congress (House and Senate), and Washington, D.C. gets three electors. The number of electors has changed throughout history as the number of elected members of Congress has changed with the countrys expansion and population growth.

Each candidate running for President in a state has their own group of electors, known as a slate, which is generally chosen by the candidates political party in the state. State laws vary on how the electors are selected and what their responsibilities are. While the Constitution does not require electors to vote for the candidate chosen by their states popular vote, some states do have laws requiring electors to vote for the candidate the party has nominated, or they have to sign pledges. In some states, electors who vote for someone other than their partys nominee may be subject to fines or disqualification and be replaced by a substitute elector.