As of the census of 2000, there were 3,689 people, 1,675 households, and 911 families residing in the borough. The population density was 6,892.2 people per square mile. There were 1,901 housing units at an average density of 3,551.7 per square mile. The racial makeup of the borough was 98.10% White, 0.43% African American, 0.11% Native American, 0.41% Asian, 0.05% from other races, and 0.89% from two or more races. Hispanic or Latino of any race were 0.54% of the population. There were 1,675 households, out of which 24.7 percent had children under the age of eighteen living with them, 35.9 percent were married couples living together, 13.8 percent had a female householder with no husband present, and 45.6 percent were non-families. Of all households, 39.3 percent were made up of individuals, and 14.6 percent had someone living alone who was sixty-five years of age or older. The average household size was 2.20 and the average family size was 2.98. In the borough the population was spread out, with 22.2 percent under the age of eighteen, 9.8 percent from eighteen to twenty-four, 30.7 percent from twenty-five to forty-four, 21.3 percent from forty-five to sixty-four, and 16 percent who were sixty-five years of age or older. The median age was thirty-seven years. For every 100 females, there were 90.9 males. For every 100 females age eighteen and over, there were 90.4 males. The median income for a household in the borough was $25,688, and the median income for a family was $34,226. Males had a median income of $30,637 versus $21,312 for females. The per capita income for the borough was $14,785. About 7.2 percent of families and 12 percent of the population were below the poverty line, including 13.6 percent of those under age 18 and 12.0 percent of those age 65 or over. As of 2019, the racial composition of the borough is approximately 72.88% White, 18.25% African American or Black and 2.12% Asian. Two or more races make up 6.01% of the population.
K-12 students in Pitcairn are served by the Gateway School District, a public school district with a student population of 4,300. In February, 2012, the Gateway School Board approved a Propel charter school proposal to open a kindergarten through 8th grade charter school within the district's borders. Propel operates 9 schools in Allegheny County. The Propel charter school re-opened the former Pitcairn Elementary Building on Agatha Street, which the Gateway board had closed in 2011. The school opened with little controversy to approximately 300 kindergarten through 6th grade students in August, 2012, with a planned expansion to 8th grade over the following two years.
