Plymouth is a town in Grafton County, New Hampshire, United States, in the White Mountains Region. Plymouth is located at the convergence of the Pemigewasset and Baker rivers. The population was 6,990 at the 2010 census. The town is home to Plymouth State University, Speare Memorial Hospital, and Plymouth Regional High School.
According to the United States Census Bureau, the town has a total area of 28.7 square miles (74.3 km), of which 28.1 square miles (72.8 km) are land and 0.58 square miles (1.5 km) are water, comprising 2.00% of the town. Plymouth is drained by the Pemigewasset and Baker rivers and lies within the Merrimack River watershed. Plymouth Mountain, elevation 2,193 feet (668 m) above sea level, the highest point in Plymouth, is in the south, and the slopes of Tenney Mountain are in the west. (The 2,310-foot (700 m) summit of Tenney Mountain lies in the town of Groton.)
The main village of Plymouth, a census-designated place, has a total area of 3.7 square miles (9.7 km). 3.7 square miles (9.5 km) of it are land and 0.077 square miles (0.2 km) of it (2.31%) are water.
As of the census of 2010, there were 6,990 people, 1,953 households, and 947 families residing in the town. The population density was 248.8 people per square mile (96.0/km). There were 2,231 housing units at an average density of 30.6 units/km (79.4 units/sq mi). The racial makeup of the town was 95.6% White, 1.0% African American, 0.3% Native American, 1.1% Asian, 0.5% some other race, and 1.6% from two or more races. Of the population 1.9% were Hispanic or Latino of any race.
There were 1,953 households, out of which 24.1% had children under the age of 18 living with them, 37.1% were headed by married couples living together, 8.6% had a female householder whose husband did not live with her, and 50.1% were non-families. 28.6% of all households were made up of individuals, and 9.9% were someone living alone who was 65 years of age or older. The average household size was 2.41, and the average family size was 2.89.
In the town, the population was spread out with 12.0% under the age of 18, 50.4% from 18 to 24, 13.3% from 25 to 44, 16.3% from 45 to 64, and 8.0% who were 65 years of age or older. The median age was 21.7 years. For every 100 females, there were 109.2 males. For every 100 females age 18 and over, there were 108.6 males.
For the period 2009–2013, the estimated median annual income for a household in the town was $41,709, and the median income for a family was $79,453. Male full-time workers had a median income of $52,297 versus $28,851 for females. The per capita income for the town was $19,804. 22.5% of the population and 3.3% of families were below the poverty line. Out of the total people living in poverty, 4.3% were under the age of 18 and 9.8% were 65 or older.