|Dearborn County, Indiana|
Dearborn County Courthouse
Location within the U.S. state of Indiana
Indiana's location within the U.S.
|Named for||Dr. Henry Dearborn|
|• Total||307.42 sq mi (796 km2)|
|• Land||305.03 sq mi (790 km2)|
|• Water||2.38 sq mi (6 km2), 0.77%|
|• ( 2010)||50,047|
|• Density||164/sq mi (63.31/km2)|
|Time zone||Eastern: UTC−5/ −4|
|Footnotes: Indiana county number 15|
Dearborn County is one of 92 counties of the U.S. state of Indiana located on the Ohio border near the southeast corner of the state. It was formed in 1803 from a portion of Hamilton County, Ohio. In 2010, the population was 50,047.  The county seat and largest city is Lawrenceburg. 
Dearborn County is part of the Cincinnati-Middletown, OH-KY-IN Metropolitan Statistical Area.
The western boundary of Ohio had been determined by the Greenville Treaty Line of 1795. In 1803 a wedge, or pie shaped, piece of land in Hamilton County east of the treaty line along Ohio's southwestern border was ceded to the Indiana Territory. It was nicknamed "The Gore," and became Dearborn County. All or part of seven other present day counties were carved from the original county with the present boundaries being established in 1845. The "Gore" area slices through the present-day counties of Dearborn, Franklin, Ohio, Randolph, Switzerland, Union, Wayne and Fayette.  Subdivision of Dearborn County began in 1811 with the formation of Franklin and Wayne Counties, followed by Switzerland in 1814. 
It was named for Gen. Henry Dearborn.  Dearborn was U.S. Secretary of War at the time the county was named. Early growth was centered on Lawrenceburg which was an important railroad junction connecting two of the regions major rail lines. 
Lawrenceburg was then designated as the county seat. However, from the start, a contention existed between the towns of Lawrenceburg and Rising Sun over that designation. The contention between the two towns was resolved in 1844 when the Indiana State legislature separated the portion of Dearborn County south of Laughery Creek and created the new county of Ohio on March 1, 1844, with Rising Sun designated as its county seat. 
According to the 2010 census, the county has a total area of 307.42 square miles (796.2 km2), of which 305.03 square miles (790.0 km2) (or 99.22%) is land and 2.38 square miles (6.2 km2) (or 0.77%) is water.  Part of the southeastern county line is formed by the Ohio River.
- Franklin County (north)
- Butler County, Ohio (northeast)
- Hamilton County, Ohio (east)
- Boone County, Kentucky (southeast)
- Ohio County (south)
- Ripley County (west)
In recent years, average temperatures in Lawrenceburg have ranged from a low of 21 °F (−6 °C) in January to a high of 86 °F (30 °C) in July, although a record low of −25 °F (−32 °C) was recorded in January 1977 and a record high of 107 °F (42 °C) was recorded in July 1988. Average monthly precipitation ranged from 2.94 inches (75 mm) in September to 5.53 inches (140 mm) in May. 
|Climate chart ( explanation)|
|U.S. Decennial Census
1790-1960  1900-1990 
1990-2000  2010-2013 
At the 2010 United States Census, there were 50,047 people, 18,743 households and 13,773 families residing in the county.  The population density was 164.1 inhabitants per square mile (63.4/km2). There were 20,171 housing units at an average density of 66.1 per square mile (25.5/km2).  The racial makeup of the county was 97.5% white, 0.6% black or African American, 0.4% Asian, 0.2% American Indian, 0.1% Pacific islander, 0.3% from other races, and 1.0% from two or more races. Those of Hispanic or Latino origin made up 1.0% of the population.  In terms of ancestry, 46.5% were German, 19.2% were Irish, 11.4% were English, and 7.8% were American. 
Of the 18,743 households, 35.1% had children under the age of 18 living with them, 58.5% were married couples living together, 10.0% had a female householder with no husband present, 26.5% were non-families, and 22.0% of all households were made up of individuals. The average household size was 2.64 and the average family size was 3.07. The median age was 40.0 years. 
The median household income was $47,697 and the median family income was $66,561. Males had a median income of $45,270 and females $33,353. The per capita income was $25,023. About 4.5% of families and 7.2% of the population were below the poverty line, including 8.5% of those under age 18 and 6.3% of those age 65 or over. 
County Council: The county council is the legislative branch of the county government and controls all the spending and revenue collection in the county. Representatives are elected from county districts. The council members serve four-year terms. They are responsible for setting salaries, the annual budget, and special spending. The council also has limited authority to impose local taxes, in the form of an income and property tax that is subject to state level approval, excise taxes, and service taxes.  
Board of Commissioners: The executive body of the county is made of a board of commissioners. The commissioners are elected county-wide, in staggered terms, and each serves a four-year term. One of the commissioners, typically the most senior, serves as president. The commissioners are charged with executing the acts legislated by the council, collecting revenue, and managing the day-to-day functions of the county government.  
Court: Dearborn County's courts consist of a Circuit Court (shared with Ohio County in the only such arrangement in the state ) and two Superior Courts. Judges are elected to six-year terms. Lawrenceburg and Aurora also have City Courts. Judges there serve four-year terms.
County Officials: The county has several other elected offices, including sheriff, prosecuting attorney, coroner, auditor, treasurer, recorder, surveyor, and circuit court clerk. Each of these elected officers serves a term of four years and oversees a different part of county government. Members elected to county government positions are required to declare a party affiliation and to be residents of the county. 
- Interstate 74
- Interstate 275
- U.S. Route 50
- U.S. Route 52
- State Road 1
- State Road 46
- State Road 48
- State Road 56
- State Road 62
- State Road 148
- State Road 262
- State Road 350
- Erwin "Cannonball" Baker, motorcycle and auto racer, 1989 inductee in Motorsports Hall of Fame of America
- John Whiteaker, first state Governor of Oregon from 1859 until 1862 and Oregon's Congressman from 1879 to 1881 
- Jim Lyttle, professional baseball player
- Lonnie Mack, influential guitar soloist of early rock 'n' roll
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- History of Dearborn and Ohio Counties, Indiana. F. E. Weakley. 1885. p. 111.
"Profile for Dearborn County, Indiana, IN". ePodunk. Retrieved August 24, 2012.
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- De Witt Clinton Goodrich & Charles Richard Tuttle (1875). An Illustrated History of the State of Indiana. Indiana: R. S. Peale & co. p. 553.
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- "Archived copy". Archived from the original on 2011-10-19. Retrieved 2011-12-03.CS1 maint: Archived copy as title ( link)
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- "Indiana House Districts". State of Indiana. Retrieved January 23, 2011.
- Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". uselectionatlas.org. Retrieved 2018-05-14.
- "John Whiteaker". Find A Grave. Retrieved August 25, 2012.