Alton is a town in Belknap County, New Hampshire, United States. The population was 5,250 at the 2010 census. It is home to Alton Bay State Forest and Mount Major State Forest.
According to the United States Census Bureau, the town has a total area of 82.2 square miles (212.9 km), of which 62.9 square miles (162.9 km) is land and 19.3 square miles (50.0 km) is water, comprising 23.49% of the town. Alton is located at the southern end of Lake Winnipesaukee, around the 4-mile-long (6.4 km) inlet known as Alton Bay. The village of Alton Bay is located at the southern tip of the bay, while the main village of Alton is located 1 mile (1.6 km) farther south. The town is drained by the Merrymeeting River, the main inlet to Alton Bay. Mount Major, in Mount Major State Forest, has an elevation of 1,780 feet (540 m) above sea level. Popular with hikers, the summit offers unsurpassed views of Lake Winnipesaukee. The highest point in Alton is the north peak of Straightback Mountain, at 1,910 ft (580 m), just west of Mount Major. Both mountains are part of the Belknap Mountains range. Alton lies almost fully within the Merrimack River watershed, though a tiny corner is in the Piscataqua River (coastal) watershed.
The town is served by five state highways. New Hampshire Route 11 passes through the center of town, leading northwest along the shore of Lake Winnipesaukee to Gilford and thence to Laconia, and southeast to Rochester. New Hampshire Route 28 also passes through the center of town, leading north to Wolfeboro and south to Pittsfield and Manchester. New Hampshire Route 140 leads from Alton west to Gilmanton and Tilton. New Hampshire Route 11A leaves NH 11 in West Alton and goes west into Gilford, and New Hampshire Route 28A forms an alternate route north from Alton Bay to NH 28.
As of the census of 2010, there were 5,250 people, 2,145 households, and 1,511 families residing in the town. There were 4,281 housing units, of which 2,136, or 49.9%, were vacant. 1,928 of the vacant units were for seasonal use. The racial makeup of the town was 98.4% white, 0.1% African American, 0.1% Native American, 0.3% Asian, 0.04% Native Hawaiian or Pacific Islander, 0.2% some other race, and 0.9% from two or more races. 1.1% of the population were Hispanic or Latino of any race.
Of the 2,145 households, 28.4% had children under the age of 18 living with them, 59.0% were headed by married couples living together, 6.9% had a female householder with no husband present, and 29.6% were non-families. 22.7% of all households were made up of individuals, and 9.5% were someone living alone who was 65 years of age or older. The average household size was 2.45, and the average family size was 2.87.
In the town, 21.1% of the population were under the age of 18, 6.2% were from 18 to 24, 20.9% from 25 to 44, 34.9% from 45 to 64, and 16.9% were 65 years of age or older. The median age was 46.2 years. For every 100 females, there were 100.8 males. For every 100 females age 18 and over, there were 99.3 males.
For the period 2011-2015, the estimated median annual income for a household was $66,823, and the median income for a family was $85,556. Male full-time workers had a median income of $46,223 versus $42,448 for females. The per capita income for the town was $29,693. 6.9% of the population and 4.6% of families were below the poverty line. 1.6% of the population under the age of 18 and 9.2% of those 65 or older were living in poverty.