Hudson County is the smallest and most densely populated county in the U.S. state of New Jersey. It lies west of the lower Hudson River, which was named for Henry Hudson, the sea captain who explored the area in 1609. Part of New Jersey's Gateway Region in the New York metropolitan area, the county seat is Jersey City, which is the county's largest city in terms of both population and area. The county is part of the North Jersey region of the state.