Mamaroneck (/məˈmærənɛk/ mə-MARR-ə-nek) is a town in Westchester County, New York, United States.
According to the United States Census Bureau, the town has a total area of 14.0 square miles (36 km), of which 6.6 square miles (17 km) is land and 7.4 square miles (19 km), or 52.85%, is water. The unincorporated area of the town measures 5.17 square miles (13.4 km).
As of the 2000 United States Census, there were 28,967 people, 10,929 households, and 7,748 families residing in the town. The population density was 4,377.5 people per square mile (1,689.5/km²). There were 11,255 housing units at an average density of 1,700.8 per square mile (656.4/km²). The racial makeup of the town was 88.93% White, 2.80% Black or African American, 0.12% Native American, 3.12% Asian, 0.05% Pacific Islander, 2.91% from other races, and 2.06% from two or more races. Hispanic of any race were 10.92% of the population.
There were 10,929 households out of which 35.6% had children under the age of 18 living with them, 60.0% were married couples living together, 8.0% had a female householder with no husband present, and 29.1% were non-families. 25.4% of all households were made up of individuals and 10.5% had someone living alone who was 65 years of age or older. The average household size was 2.62 and the average family size was 3.15.
In the town, the population was spread out with 26.1% under the age of 18, 5.1% from 18 to 24, 29.7% from 25 to 44, 24.3% from 45 to 64, and 14.8% who were 65 years of age or older. The median age was 39 years. For every 100 females, there were 91.3 males. For every 100 females aged 18 and over, there were 87.2 males.
The median income for a household in the town was $84,213, and the median income for a family was $118,774 (these figures had risen to $108,702 and $144,834 respectively as of a 2007 estimate). Males had a median income of $81,249 versus $42,703 for females. The per capita income for the town was $57,822. About 2.9% of families and 4.5% of the population were below the poverty line, including 3.7% of those under age 18 and 7.1% of those age 65 or over.