Why were the federalist papers considered a primary source?

The Federalist Papers are considered a primary source because they were written by the authors—Alexander Hamilton, James Madison, and John Jay—in the late 18th century to advocate for the ratification of the U.S. Constitution. As original documents, they provide firsthand insights into the political theories, arguments, and context surrounding the formation of the American government. Their purpose was to influence public opinion and inform the debate on constitutional issues, making them invaluable for understanding the intentions of the framers and the historical period.