The Middle Atlantic States form one of the nine geographic divisions within the United States that are officially recognized by that country's census bureau.

The division consists of only three states - New Jersey, New York State and Pennsylvania - the fewest of any of the nine divisions, but is the most densely-populated of the nine. It is one of the two divisions that constitute the United States Census Bureau's larger region of the Northeast; the other division belonging to the Northeast is New England.

The Middle Atlantic States are the anchor of America's great megalopolis, which runs from Boston to Washington, D.C.. The southeastern part of New York State, eastern Pennsylvania, and all of New Jersey combine to form the bulk of the moral region of Metropolis, according to noted socio-political geographers James Patterson and Peter Kim , co-authors of the groundbreaking 1991 book The Day America Told The Truth (Metropolis begins in the southern Connecticut suburbs of New York City and stretches along the Eastern seaboard to the northern Virginia suburbs of Washington, D.C.). The book classifies the remainder of New York State and Pennsylvania in the Rust Belt.