Calhoun County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 9,927, and was estimated to be 9,562 in 2025.

History

Calhoun County was formed on January 15, 1851, from open land originally named Fox County. It was renamed in 1853 after the seventh US vice president John C. Calhoun. When the tracks of the Illinois Central Railroad were laid through the county in 1870, the county seat was moved from Lake City to Rockwell City. The first train reached Rockwell City on August 7, 1882, and the population count doubled in the same year. The first courthouse, built of wood, burned to the ground in 1884 and the county government moved into a nearby hotel. In 1913, the current courthouse was built.

On July 6, 1893, Pomeroy was struck by a tornado that measured F5 on the Fujita scale. With a damage path wide and long, the tornado destroyed about 80% of the homes in Pomeroy. The tornado killed 71 people and injured 200.

Geography

According to the United States Census Bureau, the county has a total area of , of which is land and (0.4%) is water. It is the 48th largest county in Iowa by total area.

Ecology

Calhoun County is located entirely within the Des Moines Lobe of the Western Corn Belt Plains ecoregion, as defined by the United States Environmental Protection Agency (EPA). One of the flattest regions in Iowa, the Des Moines Lobe ecoregion is a distinctive area naturally defined by Wisconsin glaciation but modified by humans for extensive agriculture. In general, the land is level to gently rolling with some areas of relief defined by glacial features like moraines, hummocky knobs, and kettles, and outwash deposits. The lobe does not have any loess deposits like the Loess Hills to the west.

The stream network is poorly developed and widely spaced, with major rivers carving valleys that are relatively deep and steep-sided. Almost all of the natural lakes of Iowa are found in the northern part of this region (the Iowa Great Lakes). Most of the region has been converted from wet prairie to agricultural use with substantial surface water drainage. Only a small fraction of the wetlands remain, and many natural lakes have been drained as a result of agricultural drainage projects via drainage tiles or ditches.

Major highways

  • x20px U.S. Highway 20
  • x20px Iowa Highway 4
  • x20px Iowa Highway 7
  • x20px Iowa Highway 175

Adjacent counties

  • Pocahontas County (north)
  • Webster County (east)
  • Greene County (southeast)
  • Carroll County (southwest)
  • Sac County (west)

Demographics

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Education

School districts include:

  • Manson Northwest Webster Community School District
  • Newell-Fonda Community School District
  • Pocahontas Area Community School District
  • South Central Calhoun Community School District - Formed on July 1, 2014.
  • Southeast Valley Community School District - Formed on July 1, 2023. - Merged into South Central Calhoun on July 1, 2014.