Elizabeth is a city in Union County, New Jersey, in the United States. As of the 2000 census, the city had a total population of 120,568, making it New Jersey's fourth largest city. The population of Elizabeth was 126,179, as of the Census Bureau's 2006 estimate. It is the county seat of Union County. Elizabeth apartments for rent comparison page shows most up to date rent information on Elizabeth apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.