Warren County Flag

Warren County

State:
Illinois
County Seat:
Monmouth

Warren County's estimated 2025 population is 15,835 with a growth rate of -1.09% in the past year according to the most recent United States census data. Warren County is the 65th largest county in Illinois. The 2010 population was 17,710 and has seen a growth of -10.59% since that time.

15,835
Total Population
29
Population Density (mi²)
65
Population Rank (State)
-175 -1.09%
Annual Population Growth

Warren County Population

Demographics

Economics and Income Statistics