The federal government of the United States is the central government entity established by the United States Constitution, which shares sovereignty over the United States of America with the governments of the individual U.S. states. For official purposes in U.S. courts, the government is sued as (and sues others as) the United States of America, and is referred to simply as "the Government."

The U.S. federal regime dates from 1790 and is considered to be the first modern national federation in the world. Even so, the details of American federalism have been debated since the establishment and ordination of the Constitution, with some parties arguing for expansive national powers, while others have narrowly and strictly interpreted the Constitution's enumeration of the national government's powers.

Since the U.S. Civil War, the powers of the federal government have generally expanded greatly, although there have been periods when states' rights proponents have succeeded in limiting federal power through legislative action, executive prerogative or by constitutional interpretation of the courts.

The seat of the federal government is in the District of Columbia.