The Democratic Party is one of the two major contemporary political parties in the United States. Since the 1850s, its main political rival has been the Republican Party.

The Democratic Party was founded in 1828. Martin Van Buren of New York played the central role in building the coalition of state organizations that formed a new party as a vehicle to elect Andrew Jackson of Tennessee. The Democratic Party is often called the world's oldest active political party. The party supported expansive presidential power, the interests of slave states, agrarianism, and geographical expansionism, while opposing a national bank and high tariffs. It split in 1860 over slavery and won the presidency only twice in the fifty years between 1860 and 1910, although it won the popular vote a total of four times in that period. In the late 19th century, it continued to oppose high tariffs and had fierce internal debates on the gold standard. In the early 20th century, it supported progressive reforms and opposed imperialism, with Woodrow Wilson winning the White House in 1912 and 1916.

Since Franklin D. Roosevelt was elected president in 1932, the Democratic Party has promoted a social liberal platform that includes support for Social Security and unemployment insurance. The New Deal attracted strong support for the party from recent European immigrants but diminished the party's pro-business wing. From late in Roosevelt's administration through the 1950s, a minority in the party's Southern wing joined with conservative Republicans to slow and stop progressive domestic reforms. Following the Great Society era of progressive legislation under Lyndon B. Johnson, which was often able to overcome the conservative coalition in the 1960s, the core bases of the parties shifted, with the Southern states becoming more reliably Republican and the Northeastern states becoming more reliably Democratic. The party's labor union element has become smaller since the 1970s, and as the American electorate shifted in a more conservative direction following Ronald Reagan's presidency, the election of Bill Clinton marked a move for the party toward the Third Way, moving the party's economic stance towards market-based economic policy. Barack Obama oversaw the party's passage of the Affordable Care Act in 2010. During Joe Biden's presidency, the party has adopted an increasingly progressive economic agenda.

In the 21st century, the party is strongest among urban residents, union workers, college graduates, most ethnic minorities especially African Americans, the unmarried, and sexual minorities. On social issues, it advocates for abortion rights, the legalization of marijuana, and LGBT rights. On economic issues, the party favors significant increases in healthcare coverage, universal child care, paid sick leave, and supporting unions. In foreign policy, the party supports liberal internationalism, as well as tough stances against China and Russia.