Located in the northeastern corner of New Jersey and its Gateway Region, Bergen County is part of the New York City Metropolitan Area and is directly across the Hudson River from Manhattan, to which it is connected by the George Washington Bridge.

Passaic County is a county in the U.S. state of New Jersey that is part of the New York metropolitan area

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. Part of New Jersey's Gateway Region in the New York metropolitan area, Jersey City is its largest city and county seat.

The county is named after Essex, a county in the East of England. Based on data from the 2010 census, Essex County is the 14th-most densely populated county in the United States, and was ranked second in the state after Hudson County (which ranked sixth in the nation at 13,731.4 per square mile).