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Ohio Counties

There is eighty-eight counties in the state of Ohio. Washington County the oldest in the state established on July 27, 1788. Noble County was formed on March 11, 1851 from portions of Guernsey, Morgan, Monroe and Washington counties. It was the last county to be formed in Ohio and, therefore, represents the youngest county in the state.

Mercer County, Ohio

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

Mercer County is a county located in the state of Ohio. Based on the 2010 census, the population was 40,814. Its county seat is Celina. The county was created in 1820 and later organized in 1824. It is named for Hugh Mercer, an officer in the American Revolutionary War.

Mercer County comprises the Celina, OH Micropolitan Statistical Area, which is also included in the Lima-Van Wert-Celina, OH Combined Statistical Area.

Etymology - Origin of Mercer County Name

Residents named the county in honor of General Hugh Mercer, a hero of the American Revolution.


County QuickFacts: CensusBureau Quick Facts

Mercer County History

On February 12, 1820, the Ohio government authorized the creation of Mercer County. Residents named the county in honor of General Hugh Mercer, a hero of the American Revolution. In 1791, Indians defeated General Arthur St. Clair's army along the Wabash River. Once whites began to migrate to the area and canal construction began, the Miami and Erie Canal flowed through the county. To provide the canal with a water source, workers constructed Lake St. Marys in 1837. It was the largest man-made lake in the world at this time. Today, the lake is a major tourist attraction.

Mercer County is located in the northwestern part of Ohio. Its western border helps form the boundary between Ohio and Indiana. The county seat is Celina, which is the largest city in the county with a population of 10,303 people in 2000. Approximately eighty-eight percent of Mercer County's 463 square miles are covered in farms. Only 1.4 percent of the county is deemed to be urban. The county averages eighty-eight people living in each square mile. Between 1995 and 2000, the county experienced a 3.8 percent increase in population. This is unusual for Ohio's more rural counties, as residents seek better opportunities in the state's larger cities. In 2000, the county's residents numbered 40,924 people.

Most of Mercer County's residents find employment in agricultural positions. In the state, the county ranks first in hog raising, second in corn production, and third in cattle raising. Retail, manufacturing, and government positions finish second, third, and fourth respectively. In 1999, the county's per capita income was 23,376 dollars, with 6.5 percent of the county's residents living below the poverty level.

Most voters in Mercer County claim to be independents, yet in recent years, they have overwhelmingly supported Republican Party candidates at the national level

Mercer County, Ohio History Central, July 24, 2008,

Geography: Land and Water

As reported by the Census Bureau, the county has a total area of 473 square miles (1,230 km2), of which 462 square miles (1,200 km2) is land and 11 square miles (28 km2) (2.3%) is water. The entire county has an elevation difference of less than 300 feet. The highest point is on the southern county line at 1071 feet above sea level. This is in proximity to the head waters for the Wabash River. The lowest point in the county is 780 feet above sea level. This point is located on the northern county line where the St. Marys River crosses over.

Mercer County has two rivers running through it; the Wabash and the St. Marys. The Wabash watershed is part of the Gulf of Mexico's watershed. The St. Marys watershed is part of Lake Erie's watershed. Creeks between these two watersheds are within a mile of each other at some places in Mercer County. This area/line that divides the drainage basins is known as the St. Lawrence Continental Divide

Beaver Creek is the longest and largest creek in Mercer County. It stretches 19.7 miles and has two sections. The first section begins in southern farmland in the county and flows through the town of Montezuma, Ohio and into Grand Lake St. Marys. The other section of the creek begins as a spillway and empties into the Wabash River. Beaver Creek was originally one piece, but was split into two sections after the construction of Grand Lake. The creeks' spillway, and last section, has been the subject of controversy and multimillion dollar lawsuits. Farmers along Beaver Creek claim their land floods because of the spillway that was put up in 1997, replacing the previous spillway, built in 1913

Neighboring Counties

Bordering counties are as follows:

  • Van Wert County (north)
  • Auglaize County (east)
  • Shelby County (mathematical point in the southeast)
  • Darke County (south)
  • Jay County, Indiana (southwest)
  • Adams County, Indiana (northwest)


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