Butler is a borough in Morris County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 7,539, reflecting an increase of 119 (+1.6%) from the 7,420 counted in the 2000 Census, which had in turn increased by 28 (+0.4%) from the 7,392 counted in the 1990 Census.
Butler was incorporated as a borough by an act of the New Jersey Legislature on March 13, 1901, from portions of Pequannock Township.
The area now known as Butler was originally called "West Bloomingdale" and was sparsely populated. Water power brought manufacturing entities to the area. In 1857, The Pequannock Valley Paper Company moved from Bergen County and in 1868 the Newbrough Hard Rubber Company built a factory, both based along the Pequannock River. These were two significant economic entities that contributed to the growth of the Borough. In 1871, the New Jersey Midland Railroad extended track through Butler from Paterson, making an important transportation connection for both passengers and freight. The northern terminus for the New York, Susquehanna and Western Railway's passenger service was located at Butler until 1966. The railroad still carries freight through Butler.
The growing community was given the name "Butler" in 1881 after Richard Butler, who had taken ownership of the Hard Rubber Company. A Post Office was established and a larger railroad station was built.