Lyndeborough /ˈlaɪndˌbʌroʊ/ is a town in Hillsborough County, New Hampshire, United States. The population was 1,683 at the 2010 census.
According to the United States Census Bureau, the town has a total area of 30.5 square miles (79 km), of which 30.4 square miles (79 km) is land and 0.1 square miles (0.26 km) is water, comprising 0.38% of the town. The highest point in Lyndeborough is just shy of 1,800 feet (550 m) above sea level, where the east ridge of North Pack Monadnock Mountain crosses the town’s western border. Notable summits in town include Winn Mountain (1,686 ft or 514 m), Rose Mountain (1,730 ft or 530 m), and The Pinnacle (1,703 ft or 519 m). The town is crossed by state route 31.
As of the census of 2000, there were 1,585 people, 560 households, and 420 families residing in the town. The population density was 51.0 people per square mile (19.7/km²). There were 587 housing units at an average density of 18.9 per square mile (7.3/km²). The racial makeup of the town was 98.17% White, 0.19% African American, 0.13% Native American, 0.32% Asian, 0.38% from other races, and 0.82% from two or more races. Hispanic or Latino of any race were 1.64% of the population.
There were 560 households out of which 37.1% had children under the age of 18 living with them, 67.7% were married couples living together, 4.8% had a female householder with no husband present, and 25.0% were non-families. 16.4% of all households were made up of individuals and 5.7% had someone living alone who was 65 years of age or older. The average household size was 2.83 and the average family size was 3.20.
In the town, the population was spread out with 26.9% under the age of 18, 6.3% from 18 to 24, 32.6% from 25 to 44, 27.3% from 45 to 64, and 6.9% who were 65 years of age or older. The median age was 38 years. For every 100 females, there were 102.9 males. For every 100 females age 18 and over, there were 99.8 males.
The median income for a household in the town was $59,688, and the median income for a family was $70,223. Males had a median income of $37,941 versus $29,327 for females. The per capita income for the town was $27,169. About 1.2% of families and 3.3% of the population were below the poverty line, including 3.0% of those under age 18 and 8.4% of those age 65 or over.