| Term | Definition |
| Anti-Masons | Active in the 1820s and 1830s, this was considered to be the first American third party |
| Liberty | From 1840-1848 this party advocated the abolition of slavery |
| Free Soil | From 1848-1854 this party advocated no slavery in new territories |
| Know Nothing, American Party | Formed from a secret society in the 1850s, this party schemed against immigrants and Catholics |
| Constitutional Union | This party hoped to avoid a potential civil war |
| Prohibition | Founded in 1872 and still active today, this party wants to ban the production, sales, and use of alcoholic beverages |
| Greenback | From 1876-1884, this party stressed the rights of women to vote and wanted an increased money suply |
| People's Party, Populists | Active from 1892-1908, this party wanted an increased money suply and direct elections of senators |
| Socialists | Formed in 1901 and still active today, they argue for the collective ownership of the means of production |
| Communists | Formed in 1924 and still active today, this party wanted to use the government to break up trusts and monopolies and wanted to let the public control the nations resources |
| Dixiecrats | In 1948, this group of Democrats broke away from the party over the civil rights issue |
| Libertarian | Formed in 1971, this party seeks limited government and increased individual liberties |
| Reform Party | Started by businessman H. Ross Perot in 1992, this party seeks to be a new major party |
| Green Party | Nominated consumer advocate Ralph Nader for President in 2000 and is heavily active in environmental causes |