The Mid-Atlantic states, also called middle Atlantic states or simply the mid Atlantic, form a region of the United States generally located between New England and the South. Its exact definition differs upon source, but the region often includes Delaware, Maryland, New Jersey, Pennsylvania, Washington D.C., New York, Virginia, and West Virginia, though the latter two, especially Virginia, are generally considered Southern states, as are occasionally Maryland and Delaware.

The Mid-Atlantic has played an important role in the development of American culture, commerce, trade, and industry, yet it is one of the least self-conscious of American regions. It has been called "the typically American" region by Frederick Jackson Turner. Religious pluralism and ethnic diversity have been important elements of Mid-Atlantic society from its settlement by Dutch, Swedes, English Catholics, and Quakers through to the period of English rule, and beyond. After the American Revolution, the Mid-Atlantic region hosted each of the historic capitals of the United States, including the current federal capital, Washington D.C.