Petersburgh is a town located in the northeast section of Rensselaer County, New York, United States. The population was 1,525 at the 2010 census. The town was named after an early settler named Peter Simmons.
According to the United States Census Bureau, the town has a total area of 41.6 square miles (108 km), all land. On the east the town borders on the states of Massachusetts and Vermont.
The Taconic Mountains cover a great portion of the town, and the Little Hoosick River joins the Hoosic River in the north part of the town.
As of the census of 2000, there were 1,563 people, 587 households, and 433 families residing in the town. The population density was 37.6 people per square mile (14.5/km²). There were 695 housing units at an average density of 16.7 per square mile (6.5/km²). The racial makeup of the town was 98.08% White, 0.19% African American, 0.06% Native American, 0.90% Asian, 0.19% from other races, and 0.58% from two or more races. Hispanic or Latino of any race were 0.45% of the population.
There were 587 households out of which 33.9% had children under the age of 18 living with them, 62.9% were married couples living together, 7.2% had a female householder with no husband present, and 26.1% were non-families. 21.1% of all households were made up of individuals and 7.8% had someone living alone who was 65 years of age or older. The average household size was 2.66 and the average family size was 3.07.
In the town, the population was spread out with 26.2% under the age of 18, 6.5% from 18 to 24, 28.3% from 25 to 44, 26.4% from 45 to 64, and 12.5% who were 65 years of age or older. The median age was 39 years. For every 100 females, there were 103.3 males. For every 100 females age 18 and over, there were 99.3 males.
The median income for a household in the town was $45,909, and the median income for a family was $49,125. Males had a median income of $35,500 versus $25,208 for females. The per capita income for the town was $21,249. About 9.8% of families and 12.3% of the population were below the poverty line, including 16.8% of those under age 18 and 10.3% of those age 65 or over.