Sullivan County, Missouri
Sullivan County is in the northern part of Missouri. The county seat is Milan. As of 2020, about 6,000 people live there (5,999). The county was organized in 1845 and named after Major General John Sullivan from the American Revolution.
Geography
The county covers 652 square miles, almost all of it land (648 sq mi land and 3.5 sq mi water). The main creeks are Medicine, Locust, East Locust, Yellow, and Spring Creeks. The highest point is about 1,060 feet above sea level, and the lowest is about 740 feet.
History
White settlers arrived in the 1830s. Milan was founded in 1845, and the first courthouse began operating in 1847. The current three-story limestone courthouse was built in 1938 after a previous one burned. Railroads arrived in the 1870s, boosting growth. The county reached its peak population around 1900, then declined as farming changed. Agriculture—corn and other crops with family farms—remains important. A medium-sized manufacturer in Milan employs about 750 people.
People and economy
Sullivan County is very rural. In 2020, the population was 5,999. The racial makeup was mostly White (about 78%), with 17.6% Hispanic or Latino, and small percentages of Black, Native American, Asian, and other races. There were about 2,484 households, and most were owner-occupied. The median age was in the 40s. In 2010, the median household income was about $26,107, per capita income about $13,392, and around 16.5% of people were below the poverty line. The county’s economy centers on farming and a notable Milan manufacturing presence.
Government and politics
Local politics are split, with both Republicans and Democrats holding about half of the elected offices. In the state government, Sullivan County is in Missouri House District 3 (Nate Walker, Republican) and Senate District 12 (Dan Hegeman, Republican). In the U.S. Congress, it is in Missouri’s 6th District (Representative Sam Graves, Republican).
This page was last edited on 2 February 2026, at 05:24 (CET).