Delaware, constituent state of the United States of America. The first of the original 13 states to ratify the federal Constitution, it occupies a small niche in the Boston-Washington, D.C., urban corridor along the Middle Atlantic seaboard. It ranks 49th among the 50 U.S. states in terms of total area and is one of the most densely populated. The state is organised into three counties-from north to south, New Castle, Kent, and Sussex-all established by 1682. Its population, like its industry, is concentrated in the north, around Wilmington, where the major coastal highways and railways pass through from Pennsylvania and New Jersey on the north and east into Maryland on the south and west. The rest of the state comprises the northeastern corner of the Delmarva Peninsula, which Delaware shares with Maryland and Virginia (hence its name). Most state government operations are located in Dover, the capital.