Marshall County, Iowa

Marshall County, Iowa
The courthouse in Marshalltown is on the NRHP
Location within the U.S. state of Iowa
Coordinates: 42°02′30″N 92°58′53″W / 42.041700°N 92.981403°W / 42.041700; -92.981403
Country United States
State Iowa
FoundedJanuary 13, 1846
Named afterJohn Marshall
SeatMarshalltown
Largest cityMarshalltown
Area
 • Total
573.199 sq mi (1,484.58 km2)
 • Land572.503 sq mi (1,482.78 km2)
 • Water0.696 sq mi (1.80 km2)  0.12%
Population
 (2020)
 • Total
40,105
 • Estimate 
(2024)
40,392
 • Density70.052/sq mi (27.047/km2)
Time zoneUTC−6 (Central)
 • Summer (DST)UTC−5 (CDT)
Area code641
Congressional district1st
Websitemarshallcountyia.gov
  • Iowa county number 64

Marshall County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 40,105, and was estimated to be 40,392 in 2024. The county seat and largest city is Marshalltown. The county was formed on January 13, 1846, and named after John Marshall, Chief Justice of the United States Supreme Court. Marshall County comprises the Marshalltown, Iowa Micropolitan Statistical Area. In 2010, the center of population of Iowa was located in Marshall County, near Melbourne.