The People's Party, also known as the Populist Party or simply the Populists, was a left-wing[2] agrarian populist[3] late-19th-century political party in the United States. The Populist Party emerged in the early 1890s as an important force in the Southern and Western United States, but collapsed after it nominated Democrat William Jennings Bryan in the 1896 United States presidential election. A rump faction of the party continued to operate into the first decade of the 20th century, but never matched the popularity of the party in the early 1890s. The Populist Party's roots lay in the Farmers' Alliance, an agrarian movement that promoted collective economic action by farmers, as well as the Greenback Party, an earlier third party that had advocated fiat money. The success of Farmers' Alliance candidates in the 1890 elections, along with the conservatism of both major parties, encouraged Farmers' Alliance leaders to establish a full-fledged third party before the 1892 elections. The Ocala Demands laid out the Populist platform: collective bargaining, federal regulation of railroad rates, an expansionary monetary policy, and a Sub-Treasury Plan that required the establishment of federally controlled warehouses to aid farmers. Other Populist-endorsed measures included bimetallism, a graduated income tax, direct election of Senators, a shorter workweek, and the establishment of a postal savings system. These measures were collectively designed to curb the influence of corporate and financial interests and empower small farmers and laborers.

In the 1892 presidential election, the Populist ticket of James B. Weaver and James G. Field won 8.5% of the popular vote and carried four Western states, becoming the first third party since the end of the American Civil War to win electoral votes. Despite the support of labor organizers like Eugene V. Debs and Terence V. Powderly, the party largely failed to win the vote of urban laborers in the Midwest and the Northeast. Over the next four years, the party continued to run state and federal candidates, building up powerful organizations in several Southern and Western states. Before the 1896 presidential election, the Populists became increasingly polarized between "fusionists", who wanted to nominate a joint presidential ticket with the Democratic Party, and "mid-roaders", like Mary Elizabeth Lease, who favored the continuation of the Populists as an independent third party. After the 1896 Democratic National Convention nominated William Jennings Bryan, a prominent bimetallist, the Populists also nominated Bryan but rejected the Democratic vice-presidential nominee in favor of party leader Thomas E. Watson. In the 1896 election, Bryan won much of the South and West but lost to Republican William McKinley.

After the 1896 presidential election, the Populist Party suffered a nationwide collapse. The party nominated presidential candidates in the three presidential elections after 1896, but none came close to matching Weaver's performance in 1892. Former Populist voters became inactive or joined another party. Other than Debs and Bryan, few politicians associated with the Populists retained national prominence.

Historians see the Populists as a reaction to the power of corporate interests in the Gilded Age, but they debate the degree to which the Populists were anti-modern and nativist. Scholars also continue to debate the magnitude of influence the Populists exerted on later organizations and movements, such as the progressives of the early 20th century. Most of the Progressives, such as Theodore Roosevelt, Robert La Follette, and Woodrow Wilson, were bitter enemies of the Populists. In American political rhetoric, "populist" was originally associated with the Populist Party and related left-wing movements, but beginning in the 1950s it began to take on a more generic meaning, describing any anti-establishment movement regardless of its position on the left–right political spectrum