Hudson County, in the U.S. state of New Jersey, lies west of the lower Hudson River and New York City. Thecounty was named for Henry Hudson, the sea captain who explored the area in 1609. Part of New Jersey'sGateway Region in the New York metropolitan area, Jersey City is its largest city and county seat.
As of the 2010 United States Census, the county's population was 634,266, an increase of 25,291 (+4.2%) from the 608,975 enumerated in the 2000 Census, making it the fourth-most populous county in the state. Hudson County is the geographically smallest and most densely populated county in New Jersey and the sixth-most densely populated county in the United States, with 13,731.4 residents per square mile of total area in 2010.