Duncan township Flag

Duncan township

County:
Mercer County
County Seat:
No
Area (mi²):
36.636
State:
Illinois

Duncan township is located in Mercer County, Illinois. Duncan township has a 2026 population of 253. Duncan township is currently declining at a rate of -0.78% annually and its population has decreased by -3.44% since the most recent census, which recorded a population of 262 in 2020.

The median age in Duncan township is 62.4 years: 48.1 years for males, and 64.4 years for females. For every 100 females there are 115.0 males.

253
Total Population
6.9
Density (mi²)
-2 -0.78%
Growth

Duncan township Population

Duncan township Population

Data after 2023 is projected based on recent change

Year ↓
Population
Growth
Annual Change
2026253-2-0.78%
2025255-2-0.78%
2024257-2-0.77%
2023259-1-0.38%
2022260-1-0.38%
2021261-1-0.38%
2020262-1-0.38%
2019254-1-0.39%
2018255-1-0.39%
201725600%
2016256-4-1.54%
2015260-2-0.76%
2014262-3-1.13%
2013265-3-1.12%
2012268-2-0.74%
2011270-2-0.74%
2010271-1-0.37%

Median Age

Overall: 62.4 years
Female: 64.4 years
Male: 48.1 years

Duncan township Adults

There are 192 adults, (78 of whom are seniors) in Duncan township.

Sex Ratio

Female: 100 (46.5%)
Male: 115 (53.5%)

Demographics

The racial composition of Duncan township includes 100% White, and smaller percentages for and multiracial populations.

Population by Race

Race
Population ↓
Percentage (of total)
White215100%
Race
Population ↓
Percentage (of total)
White215100%

Duncan township Marital Status

Nearby Cities

Sources

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