Roselle Park is a borough in Union County, New Jersey, United States. As of the United States 2000 Census, the borough population was 13,281. Roselle Park was incorporated as a borough by an Act of the New Jersey Legislature on March 22, 1901, from portions of Union Township. The separation occurred due to a number of grievances based on a lack of sufficient public services, including; lack of a modern sewage system, poor schools, neglected roads, and minimal public safety measures.