Long Branch is a beachside city in Monmouth County, in the U.S. state of New Jersey. As of the 2020 United States census, the city's population was 31,667, an increase of 948 (+3.1%) from the 2010 census count of 30,719, which in turn reflected a decline of 621 (−2.0%) from the 31,340 counted in the 2000 census. As of the 2020 census, it was the 6th-most-populous municipality in Monmouth County and had the 74th-highest population of any municipality in New Jersey.