Williamson County Flag

Williamson County

State:
Illinois
County Seat:
Marion

Williamson County's estimated 2025 population is 67,030 with a growth rate of 0.24% in the past year according to the most recent United States census data. Williamson County is the 22nd largest county in Illinois. The 2010 population was 66,440 and has seen a growth of 0.89% since that time.

67,030
Total Population
160
Population Density (mi²)
22
Population Rank (State)
162 0.24%
Annual Population Growth

Williamson County Population

Demographics

Economics and Income Statistics