Parsippany-Troy Hills, township, Morris County, northern New Jersey, on the Rockaway River; settled about 1716, incorporated 1928 with the merger of Parsippany and Troy Hills. It is a residential and commercial community containing a number of corporate headquarters and some light industry. A state mental institution is here. The area was mainly agricultural until the 1940s. Parsippany's name is derived from a Lenni Lenape term meaning “place where the river runs through”; the origin of the name Troy Hills is unclear. Population 49,868 (1980); 48,478 (1990).
