Political parties of the United States traditionally divide the available spectrum of choices into two camps. The first is known the "major parties" and the second as the "third parties" camp. This is due to the fact that in the United States has a two-party system, with the two largest centrist parties dividing the vote between themselves in the national elections. This is partly a consequence of the first-past-the-post election system but also due to restrictive ballot access laws imposed on third parties.
Many third parties throughout U.S. history have achieved regional success and some (notably the Prohibition party and the Socialist Party of America) have had major portions of their platforms incorporated into the "major parties" platforms. While the parties in question did not go on to become one dominant players in American political life, their overall political platforms took root in the American political landscape.
Current major parties
Current "third" parties
Each of these five parties had ballot status for its presidential candidate in states with enough electoral votes to have a theoretical chance of winning in the last presidential election.
Other minor parties that have endorsed candidates
Historical political parties
Current and historical regional political parties
See: Party designation in early United States Congresses