Rock Island County, Illinois | |
|---|---|
 Rock Island County Justice Center | |
 Logo | |
 Location within the U.S. state ofIllinois | |
| Coordinates:41°28′N90°34′W / 41.47°N 90.57°W /41.47; -90.57 | |
| Country |  United States |
| State |  Illinois |
| Founded | 1831 |
| Named after | Rock (Arsenal) Island |
| Seat | Rock Island |
| Largest city | Moline |
| Area | |
• Total | 451 sq mi (1,170 km2) |
| • Land | 428 sq mi (1,110 km2) |
| • Water | 24 sq mi (62 km2) 5.2% |
| Population (2020) | |
• Total | 144,672 |
• Estimate (2024) | 142,731 [1] |
| • Density | 338/sq mi (131/km2) |
| Time zone | UTC−6 (Central) |
| • Summer (DST) | UTC−5 (CDT) |
| Congressional district | 17th |
| Website | rockislandcountyil |
Rock Island County is acounty located in theU.S. state ofIllinois, bounded on the west by theMississippi River. According to the2020 census, it had a population of 144,672.[2] Itscounty seat isRock Island; its largest city is neighboringMoline.[3] Rock Island County is one of the four counties that make up theDavenport-Moline-Rock Island,IA-ILMetropolitan Statistical Area.[4]
Rock Island County was formed in 1831 out ofJo Daviess County. It was named for Rock Island, an island in theMississippi River now known asArsenal Island.[5] TheRock River (which theSauk andMeskwaki peoples calledSinnissippi, meaning "rocky waters")[6] flows fromWhiteside County and points further east and north and joins the Mississippi River at Rock Island. TheSinnissippi Mounds, dating from the Hopewell period and on theNational Register of Historic Places are upriver atSterling in Whiteside County.
According to theU.S. Census Bureau, the county has a total area of 451 square miles (1,170 km2), of which 428 square miles (1,110 km2) is land and 24 square miles (62 km2) (5.2%) is water.[7]
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In recent years, average temperatures in the county seat of Rock Island have ranged from a low of 13 °F (−11 °C) in January to a high of 85 °F (29 °C) in July, although a record low of −22 °F (−30 °C) was recorded in February 1996 and a record high of 103 °F (39 °C) was recorded in July 2006. Average monthly precipitation ranged from 1.28 inches (33 mm) in January to 4.75 inches (121 mm) in June.[8]
| Census | Pop. | Note | %± |
|---|---|---|---|
| 1840 | 2,610 | — | |
| 1850 | 6,937 | 165.8% | |
| 1860 | 21,005 | 202.8% | |
| 1870 | 29,783 | 41.8% | |
| 1880 | 38,302 | 28.6% | |
| 1890 | 41,917 | 9.4% | |
| 1900 | 55,249 | 31.8% | |
| 1910 | 70,404 | 27.4% | |
| 1920 | 92,297 | 31.1% | |
| 1930 | 98,191 | 6.4% | |
| 1940 | 113,323 | 15.4% | |
| 1950 | 133,558 | 17.9% | |
| 1960 | 150,991 | 13.1% | |
| 1970 | 166,734 | 10.4% | |
| 1980 | 165,968 | −0.5% | |
| 1990 | 148,723 | −10.4% | |
| 2000 | 149,374 | 0.4% | |
| 2010 | 147,546 | −1.2% | |
| 2020 | 144,672 | −1.9% | |
| 2024 (est.) | 142,731 | [9] | −1.3% |
| U.S. Decennial Census[10] 1790-1960[11] 1900-1990[12] 1990-2000[13] 2010[14] | |||
As of the2020 census, the county had a population of 144,672. The median age was 40.6 years. 22.1% of residents were under the age of 18 and 19.9% of residents were 65 years of age or older. For every 100 females there were 96.8 males, and for every 100 females age 18 and over there were 94.6 males age 18 and over.[15]
The racial makeup of the county was 71.2%White, 11.5%Black or African American, 0.5%American Indian and Alaska Native, 2.8%Asian, <0.1%Native Hawaiian andPacific Islander, 5.2% from some other race, and 8.8% fromtwo or more races.Hispanic or Latino residents of any race comprised 13.7% of the population.[16]
The 2020 census counted 88.5% of residents living in urban areas and 11.5% living in rural areas.[17]
There were 60,735 households in the county, of which 27.4% had children under the age of 18 living in them. Of all households, 42.1% were married-couple households, 20.6% were households with a male householder and no spouse or partner present, and 30.0% were households with a female householder and no spouse or partner present. About 33.5% of all households were made up of individuals and 14.7% had someone living alone who was 65 years of age or older.[15]
There were 66,729 housing units, of which 9.0% were vacant. Among occupied housing units, 66.4% were owner-occupied and 33.6% were renter-occupied. The homeowner vacancy rate was 2.1% and the rental vacancy rate was 10.7%.[15]
| Race / Ethnicity(NH = Non-Hispanic) | Pop 1980[18] | Pop 1990[19] | Pop 2000[20] | Pop 2010[21] | Pop 2020[22] | % 1980 | % 1990 | % 2000 | % 2010 | % 2020 |
|---|---|---|---|---|---|---|---|---|---|---|
| White alone (NH) | 147,393 | 128,986 | 121,705 | 111,764 | 97,689 | 88.81% | 86.73% | 81.48% | 75.75% | 67.52% |
| Black or African American alone (NH) | 9,710 | 10,290 | 11,099 | 12,911 | 16,169 | 5.85% | 6.92% | 7.43% | 8.75% | 11.18% |
| Native American orAlaska Native alone (NH) | 257 | 301 | 288 | 283 | 240 | 0.15% | 0.20% | 0.19% | 0.19% | 0.17% |
| Asian alone (NH) | 889 | 980 | 1,499 | 2,383 | 4,033 | 0.54% | 0.66% | 1.00% | 1.62% | 2.79% |
| Native Hawaiian orPacific Islander alone (NH) | x[23] | x[24] | 34 | 44 | 35 | x | x | 0.02% | 0.03% | 0.02% |
| Other race alone (NH) | 510 | 82 | 109 | 135 | 482 | 0.31% | 0.06% | 0.07% | 0.09% | 0.33% |
| Mixed race or Multiracial (NH) | x[25] | x[26] | 1,849 | 2,908 | 6,182 | x | x | 1.24% | 1.97% | 4.27% |
| Hispanic or Latino (any race) | 7,209 | 8,084 | 12,791 | 17,118 | 19,842 | 4.34% | 5.44% | 8.56% | 11.60% | 13.72% |
| Total | 165,968 | 148,723 | 149,374 | 147,546 | 144,672 | 100.00% | 100.00% | 100.00% | 100.00% | 100.00% |
| Racial / Ethnic Profile of places in Rock Island County, Illinois (2020 Census) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Following is a table of towns and census designated places in Rock Island County, Illinois. Data for the United States (with and without Puerto Rico), the state of Illinois, and Rock Island County itself have been included for comparison purposes. The majority racial/ethnic group is coded per the key below. Communities that extend into and adjacent county or counties are delineated with a‡ followed by an accompanying explanatory note. The full population of each community has been tabulated including the population in adjacent counties.
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As of the2010 United States census, there were 147,546 people, 61,303 households, and 38,384 families residing in the county.[55] The population density was 345.0 inhabitants per square mile (133.2/km2). There were 65,756 housing units at an average density of 153.8 per square mile (59.4/km2).[7] The racial makeup of the county was 81.6% white, 9.0% black or African American, 1.6% Asian, 0.3% American Indian, 4.4% from other races, and 3.0% from two or more races. Those of Hispanic or Latino origin made up 11.6% of the population.[55] In terms of ancestry, 25.9% wereGerman, 14.2% wereIrish, 8.7% wereEnglish, 6.8% wereSwedish, and 5.2% wereAmerican.[56]
Of the 61,303 households, 29.0% had children under the age of 18 living with them, 45.3% were married couples living together, 12.7% had a female householder with no husband present, 37.4% were non-families, and 31.6% of all households were made up of individuals. The average household size was 2.34 and the average family size was 2.93. The median age was 40.0 years.[55]
The median income for a household in the county was $46,226 and the median income for a family was $58,962. Males had a median income of $42,548 versus $31,917 for females. The per capita income for the county was $25,071. About 8.7% of families and 12.3% of the population were below thepoverty line, including 19.0% of those under age 18 and 7.1% of those age 65 or over.[57]
At one timeMississippi Valley Airlines had its headquarters inQuad City Airport in the county.[58]John Deere is headquartered in Moline.[59]
Rock Island County is divided into eighteentownships:
Before 1932, Rock Island County was a Republican stronghold in presidential elections, backing the party's candidate in every election from 1892 to 1928. From 1932 on, it has consistently backed Democratic Party presidential candidates, except for the national Republican landslides of 1952, 1956, 1972, and 1980. In 2016,Donald Trump managed to keepHillary Clinton to a single-digit margin of victory, the first Republican to do so sinceRonald Reagan in 1984; in 2020,Joe Biden increased the Democratic margin from 8.3% to 12.1%. Due to the dominance of the Democratic Party in county politics, Rock Island County remains one of the most Democratic counties outside of the Chicago area in Illinois. Since 2010 the Republican Party began making inroads in county politics, gaining a few seats on the Democratic-dominated county board; however, since 2018, the Republican Party influence on the board has begun to decrease as the county resumed heavy Democratic voting.[60]
| Year | Republican | Democratic | Third party(ies) | |||
|---|---|---|---|---|---|---|
| No. | % | No. | % | No. | % | |
| 1892 | 5,052 | 52.38% | 4,034 | 41.82% | 559 | 5.80% |
| 1896 | 7,323 | 60.07% | 4,692 | 38.49% | 176 | 1.44% |
| 1900 | 8,299 | 61.22% | 4,786 | 35.31% | 471 | 3.47% |
| 1904 | 8,152 | 61.74% | 2,156 | 16.33% | 2,895 | 21.93% |
| 1908 | 8,196 | 55.45% | 4,739 | 32.06% | 1,846 | 12.49% |
| 1912 | 6,506 | 42.55% | 3,997 | 26.14% | 4,786 | 31.30% |
| 1916 | 16,169 | 53.17% | 10,914 | 35.89% | 3,327 | 10.94% |
| 1920 | 21,908 | 71.32% | 5,208 | 16.95% | 3,603 | 11.73% |
| 1924 | 20,563 | 57.69% | 3,631 | 10.19% | 11,453 | 32.13% |
| 1928 | 27,246 | 65.22% | 14,334 | 34.31% | 196 | 0.47% |
| 1932 | 21,205 | 45.55% | 24,676 | 53.01% | 668 | 1.44% |
| 1936 | 19,487 | 36.75% | 32,741 | 61.74% | 799 | 1.51% |
| 1940 | 25,629 | 41.95% | 35,240 | 57.67% | 232 | 0.38% |
| 1944 | 23,980 | 44.19% | 30,102 | 55.48% | 180 | 0.33% |
| 1948 | 22,192 | 47.01% | 24,542 | 51.98% | 477 | 1.01% |
| 1952 | 32,933 | 54.07% | 27,879 | 45.77% | 100 | 0.16% |
| 1956 | 31,342 | 51.72% | 29,145 | 48.09% | 118 | 0.19% |
| 1960 | 32,534 | 48.96% | 33,812 | 50.88% | 108 | 0.16% |
| 1964 | 23,714 | 36.22% | 41,759 | 63.78% | 0 | 0.00% |
| 1968 | 30,404 | 43.35% | 34,506 | 49.20% | 5,230 | 7.46% |
| 1972 | 37,548 | 53.39% | 32,529 | 46.25% | 253 | 0.36% |
| 1976 | 34,007 | 47.72% | 35,994 | 50.51% | 1,260 | 1.77% |
| 1980 | 34,788 | 48.47% | 30,045 | 41.86% | 6,942 | 9.67% |
| 1984 | 35,121 | 46.41% | 40,208 | 53.13% | 343 | 0.45% |
| 1988 | 27,412 | 40.37% | 40,174 | 59.17% | 315 | 0.46% |
| 1992 | 23,212 | 32.22% | 37,412 | 51.93% | 11,415 | 15.85% |
| 1996 | 20,626 | 33.84% | 34,822 | 57.13% | 5,507 | 9.03% |
| 2000 | 25,194 | 38.70% | 37,957 | 58.31% | 1,944 | 2.99% |
| 2004 | 29,663 | 42.39% | 39,880 | 56.99% | 429 | 0.61% |
| 2008 | 25,364 | 36.97% | 42,210 | 61.52% | 1,034 | 1.51% |
| 2012 | 24,934 | 38.23% | 39,157 | 60.04% | 1,126 | 1.73% |
| 2016 | 26,998 | 42.19% | 32,298 | 50.47% | 4,698 | 7.34% |
| 2020 | 28,603 | 42.72% | 36,691 | 54.81% | 1,653 | 2.47% |
| 2024 | 28,061 | 44.07% | 34,126 | 53.59% | 1,492 | 2.34% |
K-12 school districts include:[62]
There is one secondary school district:United Township High School District 30.[62]
Elementary school districts include:[62]
Places adjacent to Rock Island County, Illinois | |
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Municipalities and communities ofRock Island County, Illinois,United States | ||
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| Cities |  | |
| Villages | ||
| Townships | ||
| CDPs | ||
| Footnotes | ‡This populated place also has portions in an adjacent county or counties | |
| International | |
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| National | |
| Geographic | |
| Other | |
