Rock Island County, Illinois

"Rock Island County" redirects here; not to be confused with Rock Island Township.

Rock Island County, Illinois
County
Rock Island County Justice Center
Logo
Location within the U.S. state of Illinois
Coordinates: 41°28′N 90°34′W / 41.47°N 90.57°W / 41.47; -90.57
Country United States
State Illinois
Founded1831
Named afterRock (Arsenal) Island
SeatRock Island
Largest cityMoline
Area
 • Total
451 sq mi (1,170 km2)
 • Land428 sq mi (1,110 km2)
 • Water24 sq mi (62 km2)  5.2%
Population
 (2020)
 • Total
144,672
 • Estimate 
(2024)
142,731 [1]
 • Density338/sq mi (131/km2)
Time zoneUTC−6 (Central)
 • Summer (DST)UTC−5 (CDT)
Congressional district17th
Websiterockislandcountyil.gov

Rock Island County is a county located in the U.S. state of Illinois, bounded on the west by the Mississippi River. According to the 2020 census, it had a population of 144,672.[2] Its county seat is Rock Island; its largest city is neighboring Moline.[3] Rock Island County is one of the four counties that make up the Davenport-Moline-Rock Island, IA-IL Metropolitan Statistical Area.[4]

History

Rock Island County was formed in 1831 out of Jo Daviess County. It was named for Rock Island, an island in the Mississippi River now known as Arsenal Island.[5] The Rock River (which the Sauk and Meskwaki peoples called Sinnissippi, meaning "rocky waters")[6] flows from Whiteside County and points further east and north and joins the Mississippi River at Rock Island. The Sinnissippi Mounds, dating from the Hopewell period and on the National Register of Historic Places are upriver at Sterling in Whiteside County.

Geography

According to the U.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]

Climate and weather

Rock Island, Illinois
Climate chart (explanation)
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█ Average max. and min. temperatures in °F
█ Precipitation totals in inches
Source: The Weather Channel[8]
Metric conversion
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33
 
 
−1
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2
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2
−7
█ Average max. and min. temperatures in °C
█ Precipitation totals in mm

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]

Major highways

Transit

Adjacent counties

National protected area

Demographics

Historical population
CensusPop.Note%±
18402,610—
18506,937165.8%
186021,005202.8%
187029,78341.8%
188038,30228.6%
189041,9179.4%
190055,24931.8%
191070,40427.4%
192092,29731.1%
193098,1916.4%
1940113,32315.4%
1950133,55817.9%
1960150,99113.1%
1970166,73410.4%
1980165,968−0.5%
1990148,723−10.4%
2000149,3740.4%
2010147,546−1.2%
2020144,672−1.9%
2024 (est.)142,731[9] −1.3%
U.S. Decennial Census[10]
1790-1960[11] 1900-1990[12]
1990-2000[13] 2010[14]

2020 census

As of the 2020 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 and Pacific Islander, 5.2% from some other race, and 8.8% from two 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]

Racial and ethnic composition

Rock Island County, Illinois – Racial and ethnic composition
Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
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 or Alaska 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 or Pacific 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)

2010 census

As of the 2010 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% were German, 14.2% were Irish, 8.7% were English, 6.8% were Swedish, and 5.2% were American.[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 the poverty line, including 19.0% of those under age 18 and 7.1% of those age 65 or over.[57]

Economy

At one time Mississippi Valley Airlines had its headquarters in Quad City Airport in the county.[58] John Deere is headquartered in Moline.[59]

Communities

Cities

Villages

Census-designated places

Townships

Rock Island County is divided into eighteen townships:

Forts

Politics

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 keep Hillary Clinton to a single-digit margin of victory, the first Republican to do so since Ronald 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]

United States presidential election results for Rock Island County, Illinois[61]
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%

Education

K-12 school districts include:[62]

There is one secondary school district: United Township High School District 30.[62]

Elementary school districts include:[62]

  • Carbon Cliff-Barstow School District 36
  • East Moline School District 37
  • Hampton School District 29
  • Silvis School District 34

See also

Footnotes

  1. ^ "County Population Totals and Components of Change: 2020–2024". United States Census Bureau. U.S. Department of Commerce. March 2025. Retrieved August 31, 2025.
  2. ^ "Rock Island County, Illinois". United States Census Bureau. Retrieved June 10, 2023.
  3. ^ "Find a County". National Association of Counties. Archived from the original on May 31, 2011. Retrieved June 7, 2011.
  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 (PDF) on May 14, 2006. Retrieved July 21, 2006.
  5. ^ Rock Island, the island, History: Introduction Archived January 14, 2009, at the Wayback Machine, US Army Corps of Engineers
  6. ^ "Castle Rock State Park". Illinois DNR. Archived from the original on April 1, 2007. Retrieved August 3, 2014.
  7. ^ a b "Population, Housing Units, Area, and Density: 2010 - County". United States Census Bureau. Retrieved July 12, 2015.{{cite web}}: CS1 maint: deprecated archival service (link)
  8. ^ a b "Monthly Averages for Rock Island, Illinois". The Weather Channel. Archived from the original on November 12, 2009. Retrieved January 27, 2011.
  9. ^ "Population and Housing Unit Estimates Tables". United States Census Bureau. Retrieved July 24, 2025.
  10. ^ "U.S. Decennial Census". United States Census Bureau. Retrieved July 8, 2014.
  11. ^ "Historical Census Browser". University of Virginia Library. Archived from the original on August 11, 2012. Retrieved July 8, 2014.
  12. ^ "Population of Counties by Decennial Census: 1900 to 1990". United States Census Bureau. Archived from the original on April 24, 2014. Retrieved July 8, 2014.
  13. ^ "Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000" (PDF). United States Census Bureau. Archived (PDF) from the original on December 18, 2014. Retrieved July 8, 2014.
  14. ^ "State & County QuickFacts". United States Census Bureau. Archived from the original on June 7, 2011. Retrieved July 8, 2014.
  15. ^ a b c "2020 Decennial Census Demographic Profile (DP1)". United States Census Bureau. 2021. Retrieved December 25, 2025.
  16. ^ "2020 Decennial Census Redistricting Data (Public Law 94-171)". United States Census Bureau. 2021. Retrieved December 25, 2025.
  17. ^ "2020 Decennial Census Demographic and Housing Characteristics (DHC)". United States Census Bureau. 2023. Retrieved December 25, 2025.
  18. ^ "1980 Census of Population - General Population Characteristics - Illinois- Table 14 - Persons by Race and Table 16 (p. 18-28) - Total Persons and Spanish Origin Persons by Type of Spanish Origin and Race (p. 29-39)" (PDF). United States Census Bureau.
  19. ^ "1990 Census of Population - General Population Characteristics - Illinois - Table 6 - Race and Hispanic Orogin" (PDF). United States Census Bureau.
  20. ^ "P004: Hispanic or Latino, and Not Hispanic or Latino by Race – 2000: DEC Summary File 1 – Rock Island County, Illinois". United States Census Bureau.
  21. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2010: DEC Redistricting Data (PL 94-171) – Rock Island County, Illinois". United States Census Bureau.
  22. ^ a b "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Rock Island County, Illinois". United States Census Bureau.
  23. ^ included in the Asian category in the 1980 Census
  24. ^ included in the Asian category in the 1990 Census
  25. ^ not an option in the 1980 Census
  26. ^ not an option in the 1990 Census
  27. ^ a b "P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – United States by State and Territory". United States Census Bureau.
  28. ^ "P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: Dec Redistricting Data (PL 94-171) – Illinois". United States Census Bureau.
  29. ^ "P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – East Moline, Illinois". United States Census Bureau. Retrieved January 19, 2022.
  30. ^ "P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) - Moline, Illinois". United States Census Bureau. Retrieved January 19, 2022.
  31. ^ "P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Rock Island, Illinois". United States Census Bureau. Retrieved January 19, 2022.
  32. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Silvas city, Illinois". United States Census Bureau.
  33. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Andalusia village, Illinois". United States Census Bureau.
  34. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Carbon Cliff village, Illinois". United States Census Bureau.
  35. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Coal Valley village, Illinois". United States Census Bureau.
  36. ^ partly in Henry county
  37. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Cordova village, Illinois". United States Census Bureau.
  38. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Hampton village, Illinois". United States Census Bureau.
  39. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Hillside village, Illinois". United States Census Bureau.
  40. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Milan village, Illinois". United States Census Bureau.
  41. ^ "P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) - Oak Grove village, Illinois". United States Census Bureau.
  42. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Port Byron village, Illinois". United States Census Bureau.
  43. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Rapids City village, Illinois". United States Census Bureau.
  44. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Reynolds village, Illinois". United States Census Bureau.
  45. ^ partly in Mercer county
  46. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Barstow CDP, Illinois". United States Census Bureau.
  47. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Buffalo Prairie CDP, Illinois". United States Census Bureau.
  48. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Campbell's Island CDP, Illinois". United States Census Bureau.
  49. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Coyne Center CDP, Illinois". United States Census Bureau.
  50. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Edgington CDP, Illinois". United States Census Bureau.
  51. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Illinois City CDP, Illinois". United States Census Bureau.
  52. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Joslin CDP, Illinois". United States Census Bureau.
  53. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Rock Island Arsenal CDP, Illinois". United States Census Bureau.
  54. ^ "P2: Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) – Taylor Ridge CDP, Illinois". United States Census Bureau.
  55. ^ a b c "DP-1 Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data". United States Census Bureau. Retrieved July 12, 2015.{{cite web}}: CS1 maint: deprecated archival service (link)
  56. ^ "DP02 SELECTED SOCIAL CHARACTERISTICS IN THE UNITED STATES – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Retrieved July 12, 2015.{{cite web}}: CS1 maint: deprecated archival service (link)
  57. ^ "DP03 SELECTED ECONOMIC CHARACTERISTICS – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Retrieved July 12, 2015.{{cite web}}: CS1 maint: deprecated archival service (link)
  58. ^ "World Airline Directory." Flight International. March 30, 1985. 98 Archived February 23, 2013, at the Wayback Machine. "Head Office: PO Box 949, Quad City Airport, Moline, Illinois 61265, USA."
  59. ^ "Deere & Company World Headquarters". Retrieved March 21, 2019.
  60. ^ "Rock Island County Clerk - Elections - Previous Election Results".
  61. ^ Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". uselectionatlas.org. Archived from the original on March 23, 2018. Retrieved May 6, 2018.
  62. ^ a b c Geography Division (December 22, 2020). 2020 CENSUS - SCHOOL DISTRICT REFERENCE MAP: Rock Island County, IL (PDF) (Map). U.S. Census Bureau. Retrieved June 15, 2025. - Text list

Further reading

41°28′N 90°34′W / 41.47°N 90.57°W / 41.47; -90.57

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