Williamson County Flag

Williamson County

State:
Illinois
County Seat:
Marion

Williamson County's estimated 2025 population is 67,391 with a growth rate of 0.49% 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 1.43% since that time.

67,391
Total Population
160
Population Density (mi²)
22
Population Rank (State)
327 0.49%
Annual Population Growth

Williamson County Population

Demographics

Economics and Income Statistics

Sources

  1. City and Town Population Totals: 2020-2024
  2. US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
  3. US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
  4. American Community Survey (2009 - 2013)
  5. Census QuickFacts
  6. Historical Populations of States and Counties (1790 - 1990)