Pittsburg is a village in Williamson County, Illinois, United States. The population was 575 at the 2000 census.Pittsburg is located at 37°46′40″N 88°51′1″W / 37.77778°N 88.85028°W / 37.77778; -88.85028.According to the 2010 census, Pittsburg has a total area of 2.1 square miles, of which 2.07 square miles is land and 0.03 square miles is water.As of the census of 2000, there were 575 people, 228 households, and 168 families residing in the village. The population density was 275.8 people per square mile. There were 246 housing units at an average density of 118.0 per square mile. The racial makeup of the village was 98.09% White, 1.22% African American, 0.52% Native American and 0.17% Asian. Hispanic or Latino of any race were 0.17% of the population.There were 228 households out of which 30.3% had children under the age of 18 living with them, 61.0% were married couples living together, 8.3% had a female householder with no husband present, and 26.3% were non-families. 24.