|Johnson County, Iowa|
Location in the U.S. state of Iowa
Iowa's location in the U.S.
|Founded||December 21, 1837|
|Named for||Richard Mentor Johnson|
|Largest city||Iowa City|
|• Total||623 sq mi (1,614 km2)|
|• Land||614 sq mi (1,590 km2)|
|• Water||9.1 sq mi (24 km2), 1.5%|
|• ( 2010)||130,882|
|• Density||213/sq mi (82/km2)|
|Time zone||Central: UTC−6/ −5|
Johnson County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 130,882  making it the fifth-most populous county in Iowa. The county seat is Iowa City,  home of the University of Iowa. The county is named for Richard Mentor Johnson, the ninth vice president of the United States.
- 1 History
- 2 Geography
- 3 Demographics
- 4 Politics
- 5 Communities
- 6 Notable natives
- 7 See also
- 8 References
- 9 External links
Johnson County was created in December 1837 by the legislature of the Wisconsin Territory, one of thirteen counties established by that body in a comprehensive act.  The county's area was partitioned from Dubuque County, and was not initially provided with a civil government, instead being governed by Cedar County officials. It was named for the US Vice President Richard M. Johnson. 
The first courthouse in the county was a two–story log cabin structure, built in 1838 in the settlement of Napoleon,  about two miles south of the current courthouse.  The building stood across from what later would become the James McCollister Farmstead on land later owned by Philip Clark.
After Iowa City was established by fiat as the new territorial capitol of Iowa, the county seat was removed there.  The second Johnson County Courthouse, the first in Iowa City, was built on Lot 8 Block 8 of the County Seat Addition to Iowa City in 1842 for $3,690.  This location was in the southeast corner of the intersection of Harrison and Clinton Streets. The building was 56 x 28 feet and two stories tall.  It was built by James Trimble, who had previously built the first jail. 
A third courthouse was built in 1857 in the courthouse square on Clinton Street between Court and Harrison Streets. It was used until 1901, after cracks appeared in its south wall in 1899.  The building was apparently built of brick with stone and wood ornamentation. 
The Richardsonian Romanesque style courthouse in use today was designed by the firm of Rush, Bowman and Rush of Grand Rapids, MI.  It was bid at a cost of $111,000 and built by the firm Rowson & Son of Johnson County.  The cornerstone was laid in December 1899.  The building's tower was based on Henry Hobson Richardson's design for the spire of Trinity Church in Boston.  The building was dedicated on June 8, 1901.  The currently unused jail that stands to the west of the courthouse was designed by C.L. Wundt of Burlington on behalf of the Stewart Iron Works, Cleveland, OH and bid for $14,000. 
- Interstate 80
- Interstate 380
- U.S. Highway 6
- U.S. Highway 218
- Iowa Highway 1
- Iowa Highway 22
- Iowa Highway 27
- Benton County – northwest
- Cedar County – east
- Iowa County – west
- Linn County – north
- Muscatine County – east and southeast
- Louisa County – southeast and south
- Washington County – south
- Iowa County – west
|U.S. Decennial Census
1790-1960  1900-1990 
1990-2000  2010-2013 
The 2010 census recorded a population of 130,882 in the county, with a population density of 212.9964/sq mi ( 82.2384/km2). There were 55,967 housing units, of which 52,715 were occupied.
As of the census  of 2000, there were 111,006 people, 44,080 households, and 23,582 families residing in the county. The population density was 181 people per square mile (70/km²). There were 45,831 housing units at an average density of 75 per square mile (29/km²). The racial makeup of the county was 90.13% White, 2.90% Black or African American, 0.28% Native American, 4.12% Asian, 0.04% Pacific Islander, 1.01% from other races, and 1.51% from two or more races. 2.51% of the population were Hispanic or Latino of any race.
There were 44,080 households out of which 26.50% had children under the age of 18 living with them, 43.90% were married couples living together, 6.80% had a female householder with no husband present, and 46.50% were non-families. 30.20% of all households were made up of individuals and 5.60% had someone living alone who was 65 years of age or older. The average household size was 2.34 and the average family size was 2.97.
Age spread: 20.10% under the age of 18, 23.40% from 18 to 24, 30.80% from 25 to 44, 18.20% from 45 to 64, and 7.40% who were 65 years of age or older. The median age was 28 years. For every 100 females, there were 99.10 males. For every 100 females age 18 and over, there were 97.30 males.
The median income for a household in the county was $40,060, and the median income for a family was $60,112. Males had a median income of $36,279 versus $29,793 for females. The per capita income for the county was $22,220. About 5.20% of families and 15.00% of the population were below the poverty line, including 8.10% of those under age 18 and 3.80% of those age 65 or over.
Largely as a result of the presence of the University of Iowa, Johnson County is the most liberal leaning county in Iowa and a stronghold of the Democratic Party. It has been the strongest Democratic county in the state since 1984. The last Republican to win the county in a presidential election was Richard Nixon in 1960, this is true in state elections as well, where Johnson County is often the lone county to vote against the Republican in landslide elections, such as Senator Chuck Grassley's landslide re-election wins in 2010 and 2016 or Governor Terry Branstad's landslide re-election in 2014.
† county seat
|Rank||City/Town/etc.||Municipal type||Population (2010 Census)
|1||† Iowa City||City||67,862|
|4||West Branch (mostly in Cedar County)||City||2,322|
- "State & County QuickFacts". United States Census Bureau. Archived from the original on July 12, 2011. Retrieved July 18, 2014.
- "Find a County". National Association of Counties. Archived from the original on May 10, 2015. Retrieved June 7, 2011.
- United States Office of Management and Budget. "Update of Statistical Area Definitions and Guidance on Their Uses" (PDF). pp. 5, 36. Archived from the original (PDF) on May 14, 2006. Retrieved July 21, 2006.
- The other counties created on December 21, 1837: Benton, Buchanan, Cedar, Clayton, Clinton, Delaware, Fayette, Jackson, Jones, Keokuk, Linn, and Scott.
- History of Johnson County, Iowa 1836-1882 (1883). Reproduction by Unigraphic Inc. pp. 165-6.
- This no longer exists as a separate settlement but as part of Iowa City. Its former existence is recognized by the present Napoleon Park, accessed via Napoleon Lane (41.63350N, 91.53147W). Napoleon Lane Google Maps (accessed 18 August 2018)
- Aurner, p. 492.
- Aurner, pp. 47, 72.
- Aurner, pp. 21, 492.
- Aurner, p. 494.
- Aurner, p. 65.
- Daily Iowa State Press, April 1, 1899, p. 5
- Aurner, pp. 496-7.
- Aurner, p. 496.
- "The Johnson County Courthouse". Archived from the original on June 17, 2008. Retrieved July 14, 2008.
- Aurner, p. 496
- Aurner, p. 497.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. February 12, 2011. Retrieved April 23, 2011.
- "Population and Housing Unit Estimates". Retrieved June 9, 2017.
- "U.S. Decennial Census". US Census Bureau. Archived from the original on May 12, 2015. Retrieved July 18, 2014.
- "Historical Census Browser". University of Virginia Library. Retrieved July 18, 2014.
- "Population of Counties by Decennial Census: 1900 to 1990". US Census Bureau. Retrieved July 18, 2014.
- "Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000" (PDF). US Census Bureau. Retrieved July 18, 2014.
- "Population & Housing Occupancy Status 2010". US Census Bureau – American FactFinder. Retrieved May 19, 2011.
- "American FactFinder". US Census Bureau. Retrieved January 31, 2008.
- Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". uselectionatlas.org. Retrieved April 26, 2018.
- "Archived copy". Archived from the original on December 21, 2013. Retrieved February 13, 2016.
- Charles Ray Aurner, Leading Events in Johnson County, Iowa, History, Volume I (1912) reproduction by Torch Press, Cedar Rapids IA
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