What were the first political parties in American history? Why did they develop? How did they increase sectionalism in the US?

The first political parties in the United States were the Federalist Party and the Democratic-Republican Party.

The Federalist Party was founded by Alexander Hamilton in 1789, and its main ideas were those of a federal government that directly controlled the economic and tax policy of the country, protected by urban elites as a voting base, and with conservative social policies. This party controlled the destinies of the nation from 1789 to 1801, when it lost its power to the Democratic-Republican Party. Finally, in 1824 this party was dissolved.

The Democratic-Republican Party was founded in 1792 by Thomas Jefferson, with the aim of opposing the expansive policies of the federal government against the rights of the states. Although at first it did not have great relevance, from 1801 it became the main party in the country. Its platform included greater power on the part of the states and a decentralization of the American economy, in addition to a liberal social stance and a mostly agrarian voting base.

The existence of both political parties began to expose the main ideological differences in the country in the early 1800s. In other words, it demonstrated the existence of two antagonistic and irreconcilable political groups, whose differences would only exalt themselves and evolve gradually in what in 1861 ended up being the Civil War.