Missouri Counties
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Missouri Counties

Missouri has one hundred and fourteen counties and one independent city. St. Louis City is separate from St. Louis County and is referred to as a "city not within a county." Following the Louisiana Purchase and the admittance of Louisiana into the United States in 1812, five counties were formed out of the Missouri Territory at the first general assembly. Most subsequent counties were apportioned from these five original counties.

Mercer County, Missouri

Mercer County Education, Geography, and HistoryMercer County, Missouri Courthouse

Mercer County is a county located in the northwestern portion of the state of Missouri. Based on the 2010 census, the population was 3,785, making it the second-least populous county in Missouri. Its county seat is Princeton. The county was organized February 14, 1845 and named for General John F. Mercer of the Revolutionary War.

Etymology - Origin of Mercer County Name

Named for John F. Mercer, a Revolutionary War general.


County QuickFacts: CensusBureau Quick Facts

History of Mercer County

Mercer County was organized February 14, 1845. It was named in honor of "General Hugh Mercer of the Revolution." Until its organization it was a part of Grundy County. (Record of Char. County, Part I, p. 18; Campbell, p. 361; Gannett, p. 205; Rogers, p. 33; HIST. HARRISON & MERCER, p. 402)

Source: Adams, Orvyl Guy. "Place Names In The North Central Counties Of Missouri." M.A. thesis., University of Missouri-Columbia, 1928.

Geography: Land and Water

As reported by the Census Bureau, the county has a total area of 455 square miles (1,180 km2), of which 454 square miles (1,180 km2) is land and 1.3 square miles (3.4 km2) (0.3%) is water

Neighboring Counties

Bordering counties are as follows:

  • Decatur County, Iowa (northwest)
  • Wayne County, Iowa (north)
  • Putnam County (east)
  • Sullivan County (southeast)
  • Grundy County (south)
  • Harrison County (west)


Public Schools

North Mercer County R-III School District - Mercer
Princeton R-V School District - Princeton

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