The Democratic Party is a liberal political party in the United States. Sitting on the center to center-left of the political spectrum, it is the world's oldest active political party, having been founded in 1828. Its main rival is the conservative Republican Party, and since the 1850s both have dominated American politics.

It initially supported Jacksonian democracy, agrarianism, and geographical expansionism, while opposing a national bank and high tariffs. Democrats won six of the eight presidential elections from 1828 to 1856, losing twice to the Whigs. In 1860, the party split into Northern and Southern factions over slavery. The party remained dominated by agrarian interests, contrasting with Republican support for the big business of the Gilded Age. Democratic candidates won the presidency only twice between 1860 and 1908 though they won the popular vote two more times in that period. During the Progressive Era, some factions of the party supported progressive reforms, with Woodrow Wilson being elected president in 1912 and 1916.

In 1932, Franklin D. Roosevelt was elected president after campaigning on a strong response to the Great Depression. His New Deal programs created a broad Democratic coalition which united White southerners, Northern workers, labor unions, African Americans, Catholic and Jewish communities, progressives, and liberals. From the late 1930s, a conservative minority in the party's Southern wing joined with Republicans to slow and stop further progressive domestic reforms. After the civil rights movement and Great Society era of progressive legislation under Lyndon B. Johnson, who was often able to overcome the conservative coalition in the 1960s, many White southerners switched to the Republican Party as the Northeastern states became more reliably Democratic. The party's labor union element has weakened since the 1970s amid deindustrialization, and during the 1980s it lost many White working-class voters to the Republicans under Ronald Reagan. The election of Bill Clinton in 1992 marked a shift for the party toward centrism and the Third Way, shifting its economic stance toward market-based policies. Barack Obama oversaw the party's passage of the Affordable Care Act in 2010.

In the 21st century, the Democratic Party's strongest demographics are urban voters, college graduates (especially those with graduate degrees), African Americans, women, younger voters, irreligious voters, the unmarried and LGBTQ people. On social issues, it advocates for abortion rights, gun control, LGBTQ rights, action on climate change, and the legalization of marijuana. On economic issues, the party favors healthcare reform, paid sick leave, paid family leave and supporting unions. In foreign policy, the party supports liberal internationalism as well as tough stances against China and Russia.