Johnson County, Iowa

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Johnson County, Iowa
Johnson county courhouse iowa.jpg
Seal of Johnson County, Iowa
Map of Iowa highlighting Johnson County
Location in the state of Iowa
Map of the United States highlighting Iowa
Iowa's location in the U.S.
Founded 1838
Named for Richard Mentor Johnson
Seat Iowa City
Largest city Iowa City
 • Total 623.35 sq mi (1,614 km2)
 • Land 614.48 sq mi (1,591 km2)
 • Water 8.87 sq mi (23 km2), 1.42%
 • (2013) 139,155
 • Density 213/sq mi (82/km²)
Congressional district 2nd
Time zone Central: UTC-6/-5

Johnson County is a county located in the U.S. state of Iowa. The population was 139,155 in the latest United States Census Bureau 2013 population estimate[1] a 2% increase from the 2010 census.[2] The county seat is Iowa City,[3] home of the University of Iowa.

Johnson County and Washington County, Iowa make up the Iowa City metropolitan area, as defined by the US Census Bureau.[4] It is named for Richard Mentor Johnson, the ninth vice president of the United States.


According to the 2000 census, the county has a total area of 623.35 square miles (1,614.5 km2), of which 614.48 square miles (1,591.5 km2) (or 98.58%) is land and 8.87 square miles (23.0 km2) (or 1.42%) is water.[5]

Major highways[edit]

Adjacent counties[edit]


Johnson County was created on December 21, 1837 by the legislature of the Wisconsin Territory. The county was carved out of territory formerly in 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.[6]

The first courthouse in the county was a two story log cabin structure, built in 1838 in the town of Napoleon, two miles (3 km) south of Iowa City. Napoleon was located in a flood plain, however, and the second courthouse in the county was built on the hills north of Napoleon in the area that became Iowa City.

A third courthouse, built in Iowa City, was destroyed by fire on election night in 1856, while officials were busily counting votes.[citation needed] A third brick structure was built in 1857 and used until it was declared structurally unsafe in 1899. The Richardsonian Romanesque style courthouse in use today was designed and built in 1900 by the Chicago architecture firm of A.W. Rush at a cost of $111,000. The building's tower was based on Richardson's design for the spire of Trinity Church in Boston. The building was dedicated on June 8, 1901.[7]


Historical population
Census Pop.
1850 4,472
1860 17,573 293.0%
1870 24,898 41.7%
1880 25,429 2.1%
1890 23,082 −9.2%
1900 24,817 7.5%
1910 25,914 4.4%
1920 26,462 2.1%
1930 30,276 14.4%
1940 33,191 9.6%
1950 45,756 37.9%
1960 53,663 17.3%
1970 72,127 34.4%
1980 81,717 13.3%
1990 96,119 17.6%
2000 111,006 15.5%
2010 130,882 17.9%
Est. 2013 139,155 6.3%
U.S. Decennial Census[8]
2013 Estimate[1]

The US Census Bureau estimated Johnson County's population at 139,155 in 2013, second-fastest growing out of Iowa’s 99 counties after Dallas County, Iowa, a Western suburb of Des Moines, Iowa and followed by Polk County, Iowa, Scott County, Iowa and Warren County, Iowa being the top five.[1]

2010 census[edit]

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.[2]

2000 census[edit]

2000 Census Age Pyramid for Johnson County

As of the census[9] 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.

In the county the population was spread out with 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.

Notable natives[edit]



Unincorporated communities[edit]

Ghost towns[edit]


See also[edit]


  1. ^ a b c "Annual Estimates of the Resident Population: April 1, 2010 to July 1, 2013". U.S. Census Bureau, Population Division. March 2014. Retrieved 2 April 2014. 
  2. ^ a b "Population & Housing Occupancy Status 2010". United States Census Bureau American FactFinder. Retrieved May 19, 2011. 
  3. ^ "Find a County". National Association of Counties. Retrieved 2011-06-07. 
  4. ^ 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 on 2006-05-14. Retrieved 2006-07-21. 
  5. ^ "Census 2000 U.S. Gazetteer Files: Counties". United States Census. Retrieved 2011-02-13. 
  6. ^ (1883) History of Johnson County, Iowa 1836-1882 reproduction by Unigraphic Inc. p 165-166.
  7. ^ "The Johnson County Courthouse". Archived from the original on 2008-06-17. Retrieved 2008-07-14. 
  8. ^ "U.S. Decennial Census". Retrieved August 3, 2013. 
  9. ^ "American FactFinder". United States Census Bureau. Retrieved 2008-01-31. 

External links[edit]

Coordinates: 41°40′N 91°35′W / 41.667°N 91.583°W / 41.667; -91.583