The 2016 Harrisburg, Illinois, population is 8,891. There are 1,352 people per square mile (population density).
The median age is 39.9. The US median is 37.4. 42.88% of people in Harrisburg, Illinois, are married. 16.60% are divorced.
The average household size is 2.27 people. 22.38% of people are married, with children. 23.71% have children, but are single.
87.37% of people are white, 6.05% are black, 1.08% are asian, 0.42% are native american, and 0.00% claim 'Other'.
3.38% of the people in Harrisburg, Illinois, claim hispanic ethnicity (meaning 96.62% are non-hispanic).