The Democratic Party traces its origins to the Democratic-Republican Party, founded by Thomas Jefferson, James Madison, and other influential opponents of the Federalists in 1792. However, the modern Democratic Party truly arose in the 1830s, with the election of Andrew Jackson. Since the division of the Republican Party in the election of 1912, it has gradually positioned itself to the left of the Republican Party on economic and social issues. Until the period following the passage of the Civil Rights Act of 1964, the Democratic Party was primarily a coalition of two parties divided by region. Southern Democrats were typically given high conservative ratings by the American Conservative Union while northern Democrats were typically given very low ratings. Southern Democrats were a core bloc of the bipartisan conservative coalition which lasted through the Reagan-era. The economically activist philosophy of Franklin D. Roosevelt, which has strongly influenced American liberalism, has shaped much of the party's economic agenda since 1932, and served to tie the two regional factions of the party together until the late 1960s. In fact, Roosevelt's New Deal coalition usually controlled the national government until the 1970s.

In 2004, it was the largest political party, with 72 million voters (42.6% of 169 million registered) claiming affiliation. By comparison, the Republican Party has 55 million members.[5] During the first quarter of 2009, 52% of Americans identified more closely with the Democratic party while 39% leaned Republican.[7]