Johnson County, Iowa | |
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 Seal | |
 Location within the U.S. state ofIowa | |
 Iowa's location within theU.S. | |
| Coordinates:41°40′00″N91°35′00″W / 41.666666666667°N 91.583333333333°W /41.666666666667; -91.583333333333 | |
| Country |  United States |
| State |  Iowa |
| Founded | December 21, 1837 |
| Named after | Richard Mentor Johnson (1837–2020) Lulu Johnson (since 2020) |
| Seat | Iowa City |
| Largest city | Iowa City |
| Area | |
• Total | 623 sq mi (1,610 km2) |
| • Land | 614 sq mi (1,590 km2) |
| • Water | 9.1 sq mi (24 km2) 1.5% |
| Population (2020) | |
• Total | 152,854 |
• Estimate (2024)[1] | 160,080 |
| • Density | 260/sq mi (100/km2) |
| Time zone | UTC−6 (Central) |
| • Summer (DST) | UTC−5 (CDT) |
| Congressional district | 1st |
| Website | www |
Johnson County is located in theU.S. state ofIowa. As of the2020 census, the population was 152,854,[2] making it the fourth-most populous county in Iowa. Thecounty seat isIowa City,[3] home of theUniversity of Iowa. Johnson County is included in the Iowa City metropolitan area, which is also included in theCedar Rapids-Iowa City Corridor Combined Statistical Area.[4]
Johnson County was established in December 1837 by the legislature of theWisconsin Territory, one of thirteen counties established by that body in a comprehensive act.[5] The county's area was partitioned fromDubuque County, and was not initially provided with a civilgovernment, instead being governed byCedar County officials. It was originally named for the US Vice PresidentRichard M. Johnson (1780–1850).[6] In 2020, the Johnson County Board of Supervisors voted unanimously to change the county's namesake to beLulu Merle Johnson (1907–1995), the first black woman in the state to earn a doctorate. Vice President Johnson had a common law wife whom he could not marry since it was against the laws at that time to have an interracial marriage. They had two children together and she was in charge of his plantation when he was away on business. He was open about his relationship with her which was unusual for the time. Many feel that either namesake is worthy.[7]
The firstcourthouse in the county was a two-storylog cabin structure, built in 1838 in the settlement of Napoleon,[8] about two miles south of the current courthouse.[9] The building stood across from what later would become theJames 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.[10] 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.[9] 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.[11] It was built by James Trimble, who had previously built the first jail.[9]
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.[12] The building was apparently built of brick with stone and wood ornamentation.[13]
TheRichardsonian Romanesque style courthouse in use today was designed by the firm of Rush, Bowman and Rush ofGrand Rapids, Michigan.[14] It was bid at a cost of $111,000 and built by the firm Rowson & Son of Johnson County.[15] The cornerstone was laid in December 1899.[16] The building's tower was based onHenry Hobson Richardson's design for the spire ofTrinity Church in Boston.[17] The building was dedicated on June 8, 1901.[18] The currently unused jail that stands to the west of the courthouse was designed by C.L. Wundt ofBurlington, Iowa on behalf of the Stewart Iron Works inCleveland and bid for $14,000.[19]
According to theU.S. Census Bureau, the county has a total area of 623 square miles (1,610 km2), of which 614 square miles (1,590 km2) is land and 9.1 square miles (24 km2) (1.5%) is water.[20]
Interstate 80
Interstate 380
U.S. Highway 6
U.S. Highway 218
Iowa Highway 1
Iowa Highway 22
Iowa Highway 27| Census | Pop. | Note | %± |
|---|---|---|---|
| 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% | |
| 2020 | 152,854 | 16.8% | |
| 2024 (est.) | 160,080 | 4.7% | |
| U.S. Decennial Census[21] 1790–1960[22] 1900–1990[23] 1990–2000[24] 2010–2020[25]2024[26] | |||
The 2020 census recorded a population of 152,854 in the county, with a population density of245.8946/sq mi (94.94044/km2). 93.62% of the population reported being of one race. There were 65,916 housing units, of which 61,335 were occupied.[2]
| Race | Num. | Perc. |
|---|---|---|
| White (NH) | 114,491 | 74.9% |
| Black or African American (NH) | 12,643 | 8.3% |
| Native American (NH) | 193 | 0.12% |
| Asian (NH) | 8,555 | 5.6% |
| Pacific Islander (NH) | 41 | 0.03% |
| Other/Mixed (NH) | 6,733 | 4.4% |
| Hispanic orLatino | 10,198 | 6.7% |
The 2010 census recorded a population of 130,882 in the county, with a population density of212.9964/sq mi (82.2384/km2). There were 55,967 housing units, of which 52,715 were occupied.[28]
As of thecensus[29] of 2000, there were 111,006 people, 44,080 households, and 23,582 families residing in the county. The population density was 181 inhabitants 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 orAfrican American, 0.28%Native American, 4.12%Asian, 0.04%Pacific Islander, 1.01% fromother races, and 1.51% from two or more races. 2.51% of the population wereHispanic orLatino 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% weremarried 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. Theper capita income for the county was $22,220. About 5.20% of families and 15.00% of the population were below thepoverty line, including 8.10% of those under age 18 and 3.80% of those age 65 or over.
Largely due to the presence of theUniversity of Iowa, Johnson County is considered the most liberal county in Iowa and a stronghold of theDemocratic Party, and has always been among Iowa's most Democratic counties since the Civil War. It has been the strongest Democratic county in the state since1984. This trend predates the recent swing toward the Democrats in counties influenced by college towns (this trend was less prevalent inStory County, homeIowa State University inAmes, until1988). The lastRepublican to win the county in a presidential election wasRichard Nixon in 1960, and the last Republican to even get 40 percent of the county's vote wasRonald Reagan in 1984. The last time the GOP won the county in a gubernatorial election was the1978 Iowa gubernatorial election. As a measure of how strongly Democratic the county has been, Democrats easily carried it even in the national Republican landslides of 1972, 1984 and 1988, and the county was the only county in Iowa to vote for DemocratAlton B. Parker over RepublicanTheodore Roosevelt in1904. In 2020, Joe Biden received the highest percentage of the vote received by any Democrat in the county's history; indeed, by any candidate of any party.[30] In 2024, it was the only county to not vote forDonald Trump inthe state's Republican presidential caucuses.Nikki Haley won the county by a single vote.[31][32][33]
Johnson County's Democratic bent is just as pronounced at the state level. It was the lone county to vote Democratic in statewide Republican landslides, such as Senator Chuck Grassley's re-elections in2010 and2016 or Governor Terry Branstad's re-election in2014.
| Year | Republican | Democratic | Third party(ies) | |||
|---|---|---|---|---|---|---|
| No. | % | No. | % | No. | % | |
| 1880 | 2,400 | 44.89% | 2,766 | 51.74% | 180 | 3.37% |
| 1884 | 2,019 | 38.71% | 3,151 | 60.41% | 46 | 0.88% |
| 1888 | 2,051 | 40.15% | 3,038 | 59.48% | 19 | 0.37% |
| 1892 | 2,179 | 39.35% | 3,227 | 58.28% | 131 | 2.37% |
| 1896 | 2,910 | 47.06% | 3,170 | 51.26% | 104 | 1.68% |
| 1900 | 3,010 | 48.10% | 3,182 | 50.85% | 66 | 1.05% |
| 1904 | 2,963 | 48.27% | 3,085 | 50.25% | 91 | 1.48% |
| 1908 | 2,758 | 44.84% | 3,314 | 53.88% | 79 | 1.28% |
| 1912 | 1,645 | 27.95% | 3,327 | 56.52% | 914 | 15.53% |
| 1916 | 2,704 | 42.23% | 3,650 | 57.00% | 49 | 0.77% |
| 1920 | 5,696 | 52.15% | 5,032 | 46.07% | 195 | 1.79% |
| 1924 | 5,741 | 44.53% | 4,570 | 35.45% | 2,580 | 20.01% |
| 1928 | 7,288 | 50.27% | 7,181 | 49.53% | 29 | 0.20% |
| 1932 | 5,484 | 37.87% | 8,764 | 60.51% | 235 | 1.62% |
| 1936 | 5,629 | 38.18% | 8,794 | 59.65% | 320 | 2.17% |
| 1940 | 7,206 | 44.27% | 9,017 | 55.39% | 55 | 0.34% |
| 1944 | 6,396 | 42.93% | 8,434 | 56.62% | 67 | 0.45% |
| 1948 | 7,139 | 43.79% | 8,611 | 52.82% | 553 | 3.39% |
| 1952 | 11,231 | 58.04% | 8,067 | 41.69% | 52 | 0.27% |
| 1956 | 11,298 | 56.28% | 8,767 | 43.67% | 11 | 0.05% |
| 1960 | 10,927 | 50.80% | 10,563 | 49.11% | 18 | 0.08% |
| 1964 | 6,860 | 31.73% | 14,717 | 68.08% | 41 | 0.19% |
| 1968 | 11,384 | 43.88% | 13,541 | 52.19% | 1,019 | 3.93% |
| 1972 | 14,823 | 40.91% | 20,922 | 57.74% | 491 | 1.36% |
| 1976 | 16,090 | 41.57% | 20,208 | 52.20% | 2,412 | 6.23% |
| 1980 | 13,642 | 31.73% | 20,122 | 46.80% | 9,233 | 21.47% |
| 1984 | 18,677 | 41.46% | 26,000 | 57.72% | 367 | 0.81% |
| 1988 | 15,453 | 34.61% | 28,759 | 64.41% | 435 | 0.97% |
| 1992 | 14,041 | 27.12% | 28,656 | 55.35% | 9,077 | 17.53% |
| 1996 | 13,402 | 29.31% | 27,888 | 60.98% | 4,442 | 9.71% |
| 2000 | 17,899 | 33.92% | 31,174 | 59.08% | 3,696 | 7.00% |
| 2004 | 22,715 | 34.75% | 41,847 | 64.01% | 811 | 1.24% |
| 2008 | 20,732 | 28.40% | 51,027 | 69.91% | 1,230 | 1.69% |
| 2012 | 23,698 | 31.19% | 50,666 | 66.69% | 1,613 | 2.12% |
| 2016 | 21,044 | 27.35% | 50,200 | 65.25% | 5,696 | 7.40% |
| 2020 | 22,925 | 27.34% | 59,177 | 70.57% | 1,749 | 2.09% |
| 2024 | 26,087 | 30.11% | 58,846 | 67.92% | 1,711 | 1.97% |
The population ranking of the following table is based on the2020 census of Johnson County.[2]
†county seat
| Rank | City/Town/etc. | Municipal type | Population (2020 Census) |
|---|---|---|---|
| 1 | †Iowa City | City | 74,828 |
| 2 | Coralville | City | 22,318 |
| 3 | North Liberty | City | 20,479 |
| 4 | Tiffin | City | 4,512 |
| 5 | Solon | City | 3,018 |
| 6 | West Branch (mostly inCedar County) | City | 2,509 |
| 7 | Lone Tree | City | 1,357 |
| 8 | University Heights | City | 1,228 |
| 9 | Swisher | City | 914 |
| 10 | Hills | City | 863 |
| 11 | Shueyville | City | 731 |
| 12 | Oxford | City | 722 |
| 13 | Frytown | CDP | 193 |
Places adjacent to Johnson County, Iowa | ||||||||||||||||
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Municipalities and communities ofJohnson County, Iowa,United States | ||
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| Other unincorporated communities | ||
| Ghost town | ||
| Footnotes | ‡This populated place also has portions in an adjacent county or counties | |
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