Elizabeth is a city and the county seat of Union County, New Jersey, United States. As of the 2020 United States Census, the city had a total population of 137,298, making it New Jersey's fourth most populous city, after neighboring Newark, Jersey City, and Paterson, and the 203rd-most-populous in the United States.In 2008, Elizabeth was named one of "America's 50 Greenest Cities" by Popular Science magazine, the only city in New Jersey selected.