The Anti-Masonic party, the first third party in the US, was formed in the 1820s to counter the influence of the Freemasons, a secretive fraternal group. Its presidential candidate, William Wirt, captured 7.8 percent of the vote in 1832. The party pioneered the use of nominating conventions.
The Free Soil Party was started largely to stop the expansion of slavery into the Western territories. Former President Martin Van Buren, running under its banner in 1848, won 10.1 percent of the vote. The party elected several members to Congress before many of its supporters were absorbed into the Republican Party in 1854.
The American ("Know Nothing") Party was a nativist movement that flourished in the 1840s and 1850s in opposition to immigration from Europe, mainly Germans and Irish Catholics. Group members, when asked to explain their views, were told to answer "I know nothing." Former President Millard Filmore captured 21.5 percent of the vote for the party in 1856.
In 1860, the Democratic Party split over slavery. The pro-slavery Southern Democrats ran John Breckinridge, while the more liberal Northern Democrats nominated Stephen Douglas. the Constitutional Union party sought to rally support by not taking a stand on slavery and fielded John Bell. The split field helped elect Republican Abraham Lincoln.
The Populists (People's Party) sprang up in 1887 among poor farmers in the South and Plains states. They crusaded against railroads, banks, and other "elites" whom they felt were taking advantage of them. In the early 1890s, as the economy declined, industrial workers joined their ranks. The party elected a US senator from Kansas in 1890, and delivered 1 million votes for presidential hopeful James Weaver in 1892.
The Socialist Party of America formed in the early 1900s, drawing support from unionists, social reformers, and farmers. Its best presidential showing was in 1912, when Eugene V. Debs won 6 percent of the vote. Over the decades, it elected several members to Congress and more than 100 mayors before splintering in 1973.
Former President Teddy Roosevelt bolted the Republican Party when it nominated incumbent President William Howard Taft over him in 1912. He ran under the Progressive ("Bull Moose") Party label instead. Saying he was as fit as a bull moose, Roosevelt captured more of the vote than any third party candidate in history - 27 percent, besting Taft's 23 percent and helping assure the election of Democrat Woodrow Wilson.
Alabama Gov. George C. Wallace fled the Democrats and ran under the American Independent Party banner in 1968. Bluntly championing a populist and pro-segregation platform, he drew support from white Southerners and blue-collar workers weary of the civil rights movement and Vietnam War protests. He won 13.5 percent of the vote and five Southern states - and remains the last third party candidate to capture any electoral votes.
Founded in a Colorado home in 1971, The Libertarian Party today bills itself as the third largest party in the US. It espouses small government, free markets, and nonintervention in foreign policy. Its best showing in a presidential race was 1980, when oil industry lawyer Ed Clark won 1.1 percent of the vote.
After losing the GOP nomination to Ronald Reagan in 1980, Illinois Rep. John B. Anderson formed the National Unity Party to run as an Independent. He captured widespread attention - and the support of intellectuals like Gore Vidal - but only won 6.6 percent of the vote.
In 1992, Texas billionaire Ross Perot did much better running as an independent, garnering 19 percent of the vote but no electoral votes. With folksy pragmatism, he trumpeted balancing the federal budget, ending the outsourcing of jobs, and expanding the war on drugs. He represented a populist alternative to establishment politicians and at one point led all candidates in the polls.
The Tea Party of 2010 is a movement more than a sharply defined political party. It has no central leadership, no three-ring binder of detailed platform positions. Instead, it represents a loose affiliation of grass-roots groups who coalesce around issues such as dramatically downsizing government and slashing taxes and the federal deficit. Yet the movement has shaped the agenda in many races and could elect as many as 40 people to Congress. One question for 2012 and beyond: Will it be absorbed by the GOP or evolve into a third party?