What written document set up the basic government of the US?

The basic government of the United States was established by the Constitution, which was ratified in 1788. This foundational document outlines the structure of the federal government, delineates the separation of powers among the legislative, executive, and judicial branches, and includes the Bill of Rights, which guarantees individual liberties. The Constitution serves as the supreme law of the land, guiding the nation's legal framework and governance.