Long Branch, NJ. Online Offers. Long Branch is a city in Monmouth County, New Jersey, United States. As of the 2010 United States Census, the city population was 30,719. Long Branch was formed on April 11, 1867, as the Long Branch Commission, from portions of Ocean Township. Long Branch was incorporated as a city by an Act of the New Jersey Legislature on April 8, 1903, based on the results of a referendum, replacing the Long Branch Commission. Long Branch is located at 40Â°17â²53â³N 73Â°59â²27â³W / 40.297932Â°N 73.990971Â°W / 40.297932; -73.990971 (40.297932, â73.990971).