Hudson County, a county in the U.S. state of New Jersey, lies west of the lower Hudson River, which was named for Henry Hudson, the sea captain who explored the area in 1609.[4] Part of New Jersey’s Gateway Region in the New York metropolitan area, Jersey City is its largest city and county seat.
As of the 2017 Census estimate, Hudson County was the fastest-growing county in New Jersey compared to 2010; the county’s pop
ulation was 691,643, making it the state’s 4th-most populous county, an increase of 9.0% from the 2010 United States Census, when its population was enumerated at 634,266, in turn an increase of 25,291 (+4.2%) from the 608,975 enumerated in the 2000 Census. Hudson County is 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,
and 14,973.9 per square mile in 2017.
Source: Wikipedia