sentences:  Union County, New Jersey
  
  Union County is a county in the U.S. state of New Jersey.As of the 2019 Census estimate, the county's population was 556,341, making it the seventh-most populous of the state's 21 counties, an increase of 5.1% from the 2010 United States Census, when its population was enumerated at 536,499, in turn an increase of 13,958 (2.7%) from the 522,541 enumerated in the 2000 Census.