Third party (U.S. politics)

James B. Weaver won five states in 1892.

Theodore Roosevelt won six states in 1912, four more than sitting president William Howard Taft.

Robert M. La Follette won his home state of Wisconsin in 1924.

Strom Thurmond won four states in 1948.

George Wallace won five states in 1968.

Third party, or minor party, is a term used in the United States' two-party system for political parties other than the Republican and Democratic parties. The winner take all system for presidential elections and the single-seat plurality voting system for Congressional elections have over time helped establish the two-party system. Third parties are most often encountered in presidential nominations and while third-party candidates rarely win elections, they can have an effect on them through vote splitting and other impacts.

With few exceptions,^[1] the U.S. system has two major parties which have won, on average, 98% of all state and federal seats.^[2] According to Duverger's law two main political parties emerge in political systems with plurality voting in single-member districts. In this case, votes for minor parties can potentially be regarded splitting votes away from the most similar major party.^[3][4] Third party vote splitting exceeded a president's margin of victory in three elections: 1844, 2000, and 2016.

There have only been a few rare elections where a minor party was competitive with the major parties, occasionally replacing one of the major parties in the 19th century.^[4][5] No third-party candidate has won the presidency since the Republican Party became the second major party in 1856. Since then a third-party candidate won states in five elections: 1892, 1912, 1924, 1948, and 1968. 1992 was the last time a third-party candidate won over 5% of the vote and placed second in any state.^[6]