Roselle Park is a borough in Union County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 13,297, reflecting an increase of 16 from the 13,281 counted in the 2000 Census, which had in turn increased by 476 from the 12,805 counted in the 1990 Census.Roselle Park was incorporated as a borough by an act of the New Jersey Legislature on March 22, 1901, from portions of Union Township. Roselle Park's name is derived from the Roselle Land Improvement Company, which was created in 1866 to lay out a community around the Mulford Station on the Central Railroad of New Jersey. The name "Roselle" is said to have been based on the company's founder, John Conklin Rose or from John Pierre Roselle, a friend of the railroad's president.