Pittsburg is a town in Coos County, New Hampshire, United States. The population was 869 at the 2010 census. It is the northernmost town in New Hampshire and the largest town by area in New England. U.S. Route 3 is the only major highway in the town, although the northern terminus of New Hampshire Route 145 also lies within Pittsburg.
Pittsburg shares an international border with Québec province, Canada to its west and north, and borders the states of Maine (to the east) and Vermont (a very small portion to the southwest). Directly to the south is Clarksville. Pittsburg is the only New Hampshire municipality to border Canada, the only one that borders both Maine and Vermont, the only one to share a land border with Vermont, and the only town entirely north of the 45th parallel. Pittsburg contains the only part of New Hampshire west of the Connecticut River, as that river defines the Vermont state line from Clarksville southward. The Pittsburg-Chartierville Border Crossing, New Hampshire’s only Canadian border crossing, is located in the town, at the northern terminus of U.S. Route 3. The western edge of Pittsburg is defined by Halls Stream, being the “northwesternmost headwaters of the Connecticut River”, which defined (ambiguously) the border in the Treaty of Paris of 1783.
Contained within the boundaries of Pittsburg are the Connecticut Lakes, which form the beginning of the Connecticut River. Early maps (e.g. 1854) also show several grants that were incorporated into the eastern edge of Pittsburg, including Carlisle No. 1, Webster/Carlisle No. 2 and Hubbards No. 3, all north of Atkinson and Gilmanton Academy Grant.
According to the United States Census Bureau, the town has a total area of 291.2 square miles (754 km), the largest of any municipality incorporated as a town in both New Hampshire and New England. A total of 281.4 square miles (729 km) is land and 9.8 square miles (25 km) is water, the latter comprising 3.37% of the town.
The highest point in Pittsburg is the summit of Stub Hill, at 3,627 feet (1,106 m) above sea level. Mount Magalloway, 3,383 feet (1,031 m) above sea level, is a prominent summit reachable by hiking trail.
As of the census of 2000, there were 867 people, 386 households, and 264 families residing in the town. The population density was 3.1 people per square mile (1.2/km²). There were 1,281 housing units at an average density of 4.5 per square mile (1.8/km²). The racial makeup of the town was 98.27% White, 0.12% African American, 0.58% Native American, 0.23% from other races, and 0.81% from two or more races. Hispanic or Latino of any race were 0.46% of the population.
There were 386 households out of which 22.3% had children under the age of 18 living with them, 59.1% were married couples living together, 4.4% had a female householder with no husband present, and 31.6% were non-families. 26.7% of all households were made up of individuals and 14.8% had someone living alone who was 65 years of age or older. The average household size was 2.24 and the average family size was 2.67.
In the town, the population was spread out with 18.9% under the age of 18, 5.4% from 18 to 24, 23.8% from 25 to 44, 32.9% from 45 to 64, and 19.0% who were 65 years of age or older. The median age was 46 years. For every 100 females, there were 105.9 males. For every 100 females age 18 and over, there were 105.6 males.
The median income for a household in the town was $38,516, and the median income for a family was $42,500. Males had a median income of $31,250 versus $25,455 for females. The per capita income for the town was $17,703. About 5.0% of families and 7.4% of the population were below the poverty line, including 7.8% of those under age 18 and 11.5% of those age 65 or over.
In 2014 the largest ancestry groups reported in Pittsburg were English (30.9%), French or French Canadian (21.0%), Irish (9.8%), and “American” (9.2%).