Skip to content
riveryas
EN

River

Illinois River

432 km from source to mouth · United States.

United StatesUnited StatesFlows into Mississippi River

Follow the riverMonth by month

SourceMouthPeoria
The river and every tributary in its basin, drawn from RiverATLAS (CC BY 4.0).

In numbers

Length

432km

Average flow

660m³/s

Basin

104,000km²

Drop

24m

from 150 m to 126 m

Country

1

The journey

From source to mouth

432 km of river and 68 stops on the way: 38 towns and cities on its banks, dams, bridges and the tributaries that feed it.

176 m126 m
Sourceat 150 m0 km
Ottawa18,840 people52 km
Depue Lake1.2 km²95 km
Big Bureau Creektributary108 km
North Peoria113,004 people169 km
Peoria113,150 people170 km
Swan Lake5.3 km²250 km
Anderson Lake5.1 km²252 km
Meredosia Lake5.8 km²310 km
Naples100 people320 km
Calhoun County4,437 people388 km
Mississippi Riverat 126 m432 km
0100200300432 km
  1. 0 kmSourceat 150 m
  2. 0 kmDes Plaines Rivertributary
  3. 0 kmKankakee Rivertributary
  4. 14 kmMorris14,163 people
  5. 15 kmMorris Bridge
  6. 30 kmSeneca Rail Bridge
  7. 31 kmSeneca2,353 people
  8. 40 kmMarseilles4,845 people
  9. 41 kmMarseilles Bridge
  10. 52 kmOttawa18,840 people
  11. 52 kmVeterans Memorial Bridge
  12. 53 kmOttawa Rail Bridge
  13. 55 kmNaplate412 people
  14. 56 kmFox Rivertributary
  15. 68 kmUtica Bridge
  16. 71 kmDeer Park3,192 people
  17. 72 kmOglesby3,647 people
  18. 72 kmVermilion Rivertributary
  19. 74 kmLaSalle Rail Bridge
  20. 74 kmLa Salle9,609 people
  21. 75 kmShippingsport Bridge
  22. 78 kmPeru9,896 people
  23. 86 kmSpring Valley5,314 people
  24. 95 kmDepue Lake1.2 km²
  25. 101 kmHennepin769 people
  26. 108 kmBig Bureau Creektributary
  27. 120 kmHenry2,320 people
  28. 130 kmLacon Bridge
  29. 130 kmLacon1,878 people
  30. 143 kmChillicothe6,128 people
  31. 149 kmRome1,604 people
  32. 154 kmSpring Bay474 people
  33. 163 kmPeoria Heights5,979 people
  34. 165 kmMcClugage Bridge
  35. 168 kmEast Peoria22,484 people
  36. 169 kmNorth Peoria113,004 people
  37. 170 kmPeoria Lake59 km²
  38. 170 kmMurray Baker Bridge
  39. 170 kmPeoria113,150 people
  40. 172 kmWest Peoria4,418 people
  41. 176 kmCreve Coeur5,272 people
  42. 177 kmShade-Lohmann Bridge
  43. 178 kmBartonville6,382 people
  44. 185 kmPekin31,731 people
  45. 190 kmHollis Township1,829 people
  46. 191 kmMackinaw Rivertributary
  47. 196 kmKingston Mines266 people
  48. 216 kmPond Lily Lake11 km²
  49. 223 kmLiverpool94 people
  50. 235 kmSpoon Rivertributary
  51. 236 kmHavana2,963 people
  52. 236 kmScott Wike Lucas Bridge
  53. 249 kmBath279 people
  54. 250 kmSwan Lake5.3 km²
  55. 252 kmAnderson Lake5.1 km²
  56. 268 kmChain Lake7.7 km²
  57. 271 kmBrowning117 people
  58. 285 kmBeardstown5,951 people
  59. 286 kmSangamon Rivertributary
  60. 292 kmLa Moine Rivertributary
  61. 310 kmMeredosia Lake5.8 km²
  62. 312 kmMeredosia826 people
  63. 312 kmMeredosia Bridge
  64. 320 kmNaples100 people
  65. 327 kmValley City14 people
  66. 336 kmFlorence17 people
  67. 372 kmKampsville310 people
  68. 388 kmCalhoun County4,437 people
  69. 388 kmHardin801 people
  70. 432 kmMississippi Riverat 126 m

Water level along the river (RiverATLAS; the height is exaggerated). Towns: GeoNames and Wikidata; bridges, dams and tributaries: Wikidata.

Illinois tributary of the Mississippi River in the United States

At the mouth it carries 657 m³/s on average: an Olympic pool every 3.8 seconds. It drops from 150 m to 126 m, 0.1 m per kilometre on average. Its basin covers 104,000 km², about the size of IS. 6.9 million people live in it. Highest water: from April to May; lowest: from January to February. Its dams hold back little of its water (4.4% of a year's flow).

Read more on Wikipedia

Where to start

  • PeoriaLargest city on its banks · 113,150 people
  • General Wayne A. Downing Peoria International Airport (PIA)Nearest airport with scheduled flights, 9 km from the cityCar hire at PIA airport (Peoria)Discover Cars · Affiliate link
  • On the water138 ferry piers, marinas, boat rentals and boat ramps along the river (OpenStreetMap)
  • From May to SeptemberThe best months to visit

Illinois River, month by month

Highest water: from April to May

Lowest water: from January to February. Freezing months (average below −4 °C): January. Best months to visit: from May to September.

660
-5°39 mmJan
420
-2°38 mmFeb
1,700
4°75 mmMar
1,900
11°95 mmApr
2,000
17°101 mmMay
1,300
22°98 mmJun
1,200
24°101 mmJul
1,100
23°88 mmAug
1,200
19°93 mmSep
1,200
12°71 mmOct
1,200
5°70 mmNov
900
-2°62 mmDec
Water (estimated flow)Air (average) Rain (mm)Best months

From about 420 m³/s in the lowest month to 2,000 m³/s in the highest. An estimate: the monthly flow is modelled from the lowest and highest months of WaterGAP (RiverATLAS, 1971–2000) and the rain and snow along the river (WorldClim). Dams change the real rhythm. The chip is the average air temperature; below it, the month's rain.

Plan the trip

Plan the trip: boat trips, a bed by the river, a car

Car hire at PIA airport (Peoria)Discover CarsSee 

Some links above are affiliate links: if you book through them we may earn a commission, at no extra cost to you. It never changes what the data on this page says.

The basin

Illinois River: the basin in numbers

73,123 km² of land send their water to this river. This is what lives on it.

Lightly regulatedReservoirs can hold 4.4% of a year's flow.
  • 6.9millionpeople live in the basin
  • 97/km²people per km²
  • 205maverage altitude of the basin
  • 938mmof rain a year (basin average)
  • 10.3°Caverage air temperature
  • 1%protected areas
  • 0.7%covered by lakes
  • 1.2km³held in reservoirs

What covers the basin

  • 11% Forest
  • 69% Cropland
  • 4% Pasture
  • 7% Towns and cities

RiverATLAS (HydroATLAS v1.0, CC BY 4.0): land cover, people, protected areas, glaciers and dams over the whole basin upstream of the mouth.

Along the river

Illinois River: what you find on the way

  • 47DamsSpillway, Tainter Gates, Earthen Embankment and 44 more
  • 8WeirsIce Chute, Peoria Dam, La Grange Dam and 5 more
  • 16LocksDresden Island Lock Canal, Illinois River, Ice Chute and 13 more
  • 140WaterfallsOttawa Canyon Waterfall, Wildcat Canyon Waterfall, Saint Louis Canyon Waterfall and 137 more
  • 115Boat rampsHenry Marina, Lacon Public Access, Chillicothe Access Area and 112 more
  • 7Ferry piersKampsville Ferry, Brussels Ferry (South Dock), Brussels Ferry (North Dock) and 4 more
  • 16MarinasSpring Brook Marina, Henry Marina, Lacon Marina and 13 more

From OpenStreetMap, within 2.3 km of the river. Not mapped is not the same as not there.

Cross-checked with our atlases

Illinois River in our other atlases

What our sister atlases know about the waterfalls on this river, the lakes it flows through, the beaches at its mouth, the mountains where it rises and the islands off its mouth.

  • 7lakes on its wayLakeyas

Lakes and reservoirs (7)

Lakes it flows through, by Lakeyas

  1. Depue Lakekm 1011.2km²
  2. Peoria Lakekm 17959km²
  3. Pond Lily Lakekm 22811km²
  4. Swan Lakekm 2645.3km²
  5. Anderson Lakekm 2655.1km²
  6. Chain Lakekm 2827.7km²
  7. Meredosia Lakekm 3275.8km²

Lakeyas is coming soonOpen Lakeyas ↗

From space

The source and the mouth, seen from orbit

Illinois River: satellite view of the source
The source14 km across
Illinois River: satellite view of the mouth
The mouth37 km across

Sentinel-2 cloudless 2016 by EOX IT Services GmbH (contains modified Copernicus Sentinel data 2016), CC BY 4.0. The glowing line is the river as drawn by RiverATLAS.

Photos

Illinois River in pictures

Illinois River, seen from Starved Rock
en:User:RedWordSmith · CC BY-SA 3.0
Illinois River near LaSalle Illinois
Joseph Norton and Ronald Frazier · CC BY 2.0
Dam on Illinois River, Starved Rock, Illinois, April 2009
HeatherMarieKosur · CC BY-SA 4.0
Gfp-illinois-starved-rock-state-park-across-the-river
Yinan Chen · Public Domain

Tributaries

Where it flows, and what flows into it

It flows into

Mississippi RiverUnited StatesUnited States3,766 km12,700 m³/s

Tributaries (13)

Also: Kankakee River, Des Plaines River, Sangamon River, Fox River, La Moine River, Mackinaw River, Spoon River, Vermilion River, Big Bureau Creek, Macoupin Creek, Mazon River, Little Vermilion River, Kickapoo Creek

In the same basin

Missouri RiverUnited StatesUnited States3,726 km2,500 m³/sOhio RiverUnited StatesUnited States1,579 km8,000 m³/sArkansas RiverUnited StatesUnited States2,364 km240 m³/sTennessee RiverUnited StatesUnited States1,049 km2,000 m³/sRed RiverUnited StatesUnited States2,189 km1,900 m³/sYellowstone RiverUnited StatesUnited States1,114 km390 m³/sPlatte RiverUnited StatesUnited States500 km200 m³/sCanadian RiverUnited StatesUnited States1,458 km200 m³/sAllegheny RiverUnited StatesUnited States523 km560 m³/sCumberland RiverUnited StatesUnited States1,107 km860 m³/s

Nearby

Rivers nearby

Missouri RiverUnited StatesUnited States3,726 km2,500 m³/s34 km awayOsage RiverUnited StatesUnited States444 km310 m³/s133 km awayDes Moines RiverUnited StatesUnited States845 km250 m³/s177 km awayOhio RiverUnited StatesUnited States1,579 km8,000 m³/s249 km awayTennessee RiverUnited StatesUnited States1,049 km2,000 m³/s267 km awayWabash RiverUnited StatesUnited States960 km1,000 m³/s249 km awayCumberland RiverUnited StatesUnited States1,107 km860 m³/s271 km awayIowa RiverUnited StatesUnited States520 km280 m³/s249 km away

Where these numbers come from

Name, length, placesWikidata (Q8321) · CC0
Course, profile, basinRiverATLAS v1.0 (HydroATLAS, Linke et al. 2019) · CC BY 4.0 — followed from the source to the mouth given by Wikidata
FlowWaterGAP (RiverATLAS), 1971–2000 · CC BY 4.0
Climate along the riverWorldClim (RiverATLAS), 1970–2000 · CC BY 4.0
Towns, bridges, damsWikidata · CC0; GeoNames · CC BY 4.0
Along the river© OpenStreetMap contributors · ODbL
ImagesEOX Sentinel-2 cloudless 2016 · CC BY 4.0; Wikimedia Commons
Our other atlasesLakeyas — Wikidata · CC0; © OpenStreetMap contributors · ODbL; GeoNames · CC BY 4.0; HydroLAKES · CC BY 4.0; NOAA OISST

Every source and licence is on the data sources page.

The family

Do you prefer beaches, lakes, mountains, waterfalls, islands, rivers or canyons?

Same idea, other landscapes: field atlases built on open data, month by month, in seven languages.

beachesCoastyaFind your beach: sea temperature, sun and swimming month by month.Visit
lakesLakeyasEvery lake on Earth: water temperature, ice, depth and the shore.Coming soonVisit
mountainsPeakyasEvery summit in 3D: summit weather, the 0 °C line, huts and trails.Visit
waterfallsCascadyasEvery waterfall: height, flow month by month and when it roars.Coming soonVisit
islandsIslandyasEvery island from the sea up: size, sea temperature, ferries and 3D.Coming soonVisit
riversRiveryasEvery river from source to sea: the journey, the flow and the basin in numbers.You are here
canyonsCanyonyasEvery canyon cut to scale: depth to the floor, rim and floor temperatures, trails and viewpoints.Coming soonVisit