Pittsburg had a population of 20,646, with 8,268 households and 4,123 families. The population density was 1,578.9 per square mile (609.6/km). There were 9,650 housing units at an average density of 738.0 per square mile (284.9/km), of which 14.3% were vacant; the homeowner vacancy rate was 3.3% and the rental vacancy rate was 12.0%. 97.4% of residents lived in urban areas, while 2.6% lived in rural areas.

The median age was 27.7 years. 21.9% of residents were under the age of 18; 23.9% were from 18 to 24; 23.7% were from 25 to 44; 17.8%