On this day in 1854, the Republican Party was founded in a schoolhouse in Ripon, Wisconsin as an anti-slavery party. By 1860, the party controlled the northern states and the White House, following the election of Abraham Lincoln.
Two political parties have always generally dominated the U.S. political system. The Democratic Party, founded in the 1790s, is the oldest, and has participated in every election since then. Before 1854, several parties vied to be that dominant second major party. There was the Whig Party, the Free Soil Party and the Know-Nothing Party. Members of the all of those parties found a home in the Republican Party.
Both the Democrats and Republicans have changed with the country. Aside from a few unique instances in American history, most notably the third party candidacies of Theodore Roosevelt, George Wallace and Ross Perot, the Democrats and Republicans have seen no viable threat to their dominance of U.S. politics.