Belmar is a borough in Monmouth County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 5,794, reflecting a decline of 251 (-4.2%) from the 6,045 counted in the 2000 Census, which had in turn increased by 168 (+2.9%) from the 5,877 counted in the 1990 Census.
What is now Belmar was originally incorporated as Ocean Beach borough by an act of the New Jersey Legislature on April 9, 1885, from portions of Wall Township, based on the results of a referendum held two days earlier. On April 16, 1889, it became the City of Elcho borough, which lasted for a few weeks until the name was changed to the City of Belmar Borough as of May 14, 1889. The city acquired its current name, Borough of Belmar, on November 20, 1890. The borough's name means "beautiful sea" in Italian.
According to the United States Census Bureau, the borough had a total area of 1.62 square miles (4.18 km2), including 1.05 square miles (2.71 km2) of land and 0.57 square miles (1.48 km2) of water (35.19%).
Belmar borders the Atlantic Ocean to the east, and the Monmouth County municipalities of Avon-by-the-Sea to the north, Neptune Township to the northwest, Wall Township to the west, and Lake Como and Spring Lake to the south.
The 2010 United States Census counted 5,794 people, 2,695 households, and 1,267 families in the borough. The population density was 5,544.0 inhabitants per square mile (2,140.6/km2). There were 3,931 housing units at an average density of 3,761.4 per square mile (1,452.3/km2). The racial makeup was 87.06% (5,044) White, 3.49% (202) Black or African American, 0.24% (14) Native American, 0.91% (53) Asian, 0.14% (8) Pacific Islander, 5.66% (328) from other races, and 2.50% (145) from two or more races. Hispanic or Latino of any race were 16.76% (971) of the population.
Of the 2,695 households, 18.1% had children under the age of 18; 33.9% were married couples living together; 8.8% had a female householder with no husband present and 53.0% were non-families. Of all households, 41.9% were made up of individuals and 12.1% had someone living alone who was 65 years of age or older.