Lewisboro is a town in Westchester County, New York, United States. The population was 12,411 at the 2010 census. The town is named after John Lewis, an early settler.
The census of 2000 counted 12,324 people residing in the town, living in 4,218 households, of which 3,425 were families. The population density was 442.5 people per square mile (170.9/km²). There were 4,465 housing units at an average density of 160.3 per square mile (61.9/km²). The racial makeup of the town was 95.18% White, 1.19% African American, 0.06% Native American, 2.09% Asian, 0.49% from other races, and 0.99% from two or more races. Hispanic or Latino of any race were 2.48% of the population.
There were 4,218 households, of which 47.4% had children under the age of 18 living with them, 72.9% were married couples living together, 6.7% had a female householder with no husband present, and 18.8% were non-families. 15.2% of all households were made up of individuals and 4.1% had someone living alone who was 65 years of age or older. The average household size was 2.91 and the average family size was 3.26.
In the town the population was spread out with 31.6% under the age of 18, 3.8% from 18 to 24, 28.5% from 25 to 44, 29.0% from 45 to 64, and 7.1% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 95.8 males. For every 100 females age 18 and over, there were 92.3 males.
The median income for a household in the town was $112,462, and the median income for a family was $157,412. Males had a median income of $84,616 versus $48,900 for females. The per capita income for the town was $54,795. About 1.4% of families and 1.9% of the population were below the poverty line, including 1.3% of those under age 18 and 2.7% of those age 65 or over.