Rockaway is a borough in Morris County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 6,438, reflecting a decline of 35 from the 6,473 counted in the 2000 Census, which had in turn increased by 230 from the 6,243 counted in the 1990 Census.Rockaway was formed as a borough on June 19, 1894, from portions of Rockaway Township, based on the results of a referendum held the previous day. Additional portions of Rockaway Township were annexed by the borough in 1908.The borough shares its name with the Rockaway River and the neighboring township. The name is derived from a Native American term, variously said to mean "place of sands", "creek between two hills" or "bushy" / "difficult to cross".