Delaware ( (listen)) is one of the 50 states of the United States, in the Mid-Atlantic or Northeastern region. It is bordered to the south and west by Maryland, north by Pennsylvania, and east by New Jersey and the Atlantic Ocean. The state takes its name from Thomas West, 3rd Baron De La Warr, an English nobleman and Virginia's first colonial governor.Delaware occupies the northeastern portion of the Delmarva Peninsula. It is the second smallest and sixth least populous state, but the sixth most densely populated. Delaware's largest city is Wilmington. The state is divided into three counties, the lowest number of any state. From north to south, they are New Castle County, Kent County, and Sussex County. While the southern two counties have historically been predominantly agricultural, New Castle County is more industrialized.
Before its coastline was explored by Europeans in the 16th century, Delaware was inhabited by several groups of Native Americans, including the Lenape in the north and Nanticoke in the south. It was initially colonized by Dutch traders at Zwaanendael, near the present town of Lewes, in 1631. Delaware was one of the 13 colonies participating in the American Revolution. On December 7, 1787, Delaware became the first state to ratify the Constitution of the United States, and has since been known as "The First State".