As of the 2000 census, there were 1,989 people, 737 households, and 577 families residing in the township. The population density was . There were 777 housing units at an average density of . The racial makeup of the township was 98.34% White, 0.40% African American, 0.15% Native American, 0.10% Asian, and 1.01% from two or more races. Hispanic or Latino of any race were 0.90% of the population.
There were 737 households, out of which 35.7% had children under the age of 18 living with them, 61.9% were married couples living together, 10.2% had a female householder with no husband present, and 21.6% were non-families. 19.7% of all households were made up of individuals, and 9.9% had someone living alone who was 65 years of age or older. The average household size was 2.70 and the average family size was 3.04.
In the township the population was spread out, with 25.2% under the age of 18, 7.3% from 18 to 24, 29.6% from 25 to 44, 24.5% from 45 to 64, and 13.4% who were 65 years of age or older. The median age was 39 years. For every 100 females, there were 99.5 males. For every 100 females age 18 and over, there were 98.9 males.
The median income for a household in the township was $29,279, and the median income for a family was $33,125. Males had a median income of $30,985 versus $23,403 for females. The per capita income for the township was $13,568. About 14.6% of families and 17.6% of the population were below the poverty line, including 24.6% of those under age 18 and 11.5% of those age 65 or over.
Government
Nicholson Township is governed by a Board of Supervisors duly elected by the citizens of the township with offices at the Nicholson Township Building located at 142 Woodside-Old Frame Road in Smithfield. The current Township Supervisors are John Black of Old Frame, Jack Arndt, of Jacobs Creek Road, and Richard Jarrett, of Boy Scout Road. Said supervisors serve staggered six-year terms. The Township Engineer is Pole Star Engineering located in Uniontown, and the Township Solicitor is Douglas Sholtis, a resident of the township.
Notable person
Isaac Griffin (1756–1827), a politician who represented Pennsylvania in the U.S. House of Representatives, made his home in Nicholson Township. He is buried within the boundaries of the township, but the site of his grave is now unknown.