Mid-Atlantic (United States) (Wikipedia) The Mid-Atlantic is a region of the United States located in the overlap between the Northeastern and Southeastern states of the United States. The region typically includes five states, New York, New Jersey, Pennsylvania, Delaware, and Maryland, and the national capital of Washington, D.C.. Virginia and West Virginia are sometimes included in definitions of the region’s geography. The region has its origin in 18th century, and its states were each among the Thirteen Colonies of pre-revolutionary British America.