Manhattan (coterminous with New York County) is an islan borough within New York City, with a 2007 population of 1,620,867 living in a land area of 22.96 square miles (59.47 km²), it is the most densely populated county in the United States at 70,595 residents per square mile (27,267/km²). It is also the wealthiest county in the United States, with a 2005 personal per capita income above $100,000.00. The borough consists of Manhattan Island, Roosevelt Island, Randalls Island, almost one-tenth of Ellis Island, the above-water portion of Liberty Island, several much smaller islands, and a small section on the mainland of New York State adjacent to the Bronx.