How many people live in Sullivan County, MO?
Updated Apr. 6, 2026Refreshed annually
In 2024, there were about 5,800 people living in Sullivan County, MO. That makes Sullivan County the 106th-most populous county in Missouri. It is home to 0.09% of people living in the state.
5.75K
population of Sullivan County, MO (2024)
0.09%
County share of the Missouri population (2024)
About 5,800 people lived in Sullivan County, MO in 2024.
Population estimates, 2000–2024
What are Sullivan County, MO’s age demographics?
About 1,300 Sullivan County, MO residents are aged 65 and older in 2024. That represents 22.7% of its population. For comparison, the age group represents 18.8% of Missouri’s population and 18% in the US overall.
Another 1,200 Sullivan County residents, or 21.5% of the population, were children under 18. For comparison, the age group represents 22% of Missouri’s population and 21.6% in the US overall.
A lower share of Sullivan County, MO's population is aged 25–44 than the US as a whole.
Population estimates by age group, (2024)
What are Sullivan County, MO’s racial and ethnic demographics?
Non-Hispanic white residents make up 76.1% of the Sullivan County, MO population, higher than the national share of 57.5%. Sullivan County, MO also has a larger share of people identifying as non-Hispanic American Indian and Alaska Native (0.73%) than the US overall (0.72%).
In contrast, Sullivan County’s non-Hispanic Black or African American population accounts for 2.8%, below the 12.6% nationwide, and the non-Hispanic Asian population makes up 0.43% of the county, compared with 6.5% nationally.
Racial and ethnic make up differ based on location. These figures reflect how people identified their race alone (not in combination with other races), and separate out Hispanic or Latino ethnicity, following Census reporting standards.
Sullivan County, MO has a higher share of a Hispanic population than Missouri as a whole.
Population estimates by race and ethnicity, (2024)
The largest city or town in Sullivan County, MO is Milan with about 1,700 residents in 2024.
Cities and towns in Sullivan County, MO ranked by population
Population (2024), includes only portions within county
| City or town | Population | |
|---|---|---|
| 1. | Milan | 1,749 |
| 2. | Green City | 570 |
| 3. | Green Castle | 209 |
| 4. | Newtown | 110 |
| 5. | Humphreys | 88 |
| 6. | Harris | 59 |
| 7. | Browning (pt.) | 55 |
| 8. | Pollock | 44 |
| 9. | Osgood | 22 |
| 10. | Balance of Sullivan County | 2,844 |
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Methodology
USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.
The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.
Page sources
USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.
