| Rank |
County |
Land Area |
| 1 |
McLean County, Illinois
|
1,183.4
|
| 2 |
LaSalle County, Illinois
|
1,135.1
|
| 3 |
Iroquois County, Illinois
|
1,117.3
|
| 4 |
Livingston County, Illinois
|
1,044.3
|
| 5 |
Champaign County, Illinois
|
996.3
|
| 6 |
Cook County, Illinois
|
945.3
|
| 7 |
Vermilion County, Illinois
|
898.4
|
| 8 |
Bureau County, Illinois
|
869.0
|
| 9 |
Sangamon County, Illinois
|
868.3
|
| 10 |
Fulton County, Illinois
|
865.6
|
| 11 |
Macoupin County, Illinois
|
862.9
|
| 12 |
Adams County, Illinois
|
855.2
|
| 13 |
Will County, Illinois
|
836.9
|
| 14 |
Pike County, Illinois
|
831.4
|
| 15 |
Henry County, Illinois
|
823.0
|
| 16 |
Hancock County, Illinois
|
793.7
|
| 17 |
Ogle County, Illinois
|
758.6
|
| 18 |
Shelby County, Illinois
|
758.5
|
| 19 |
Lee County, Illinois
|
724.9
|
| 20 |
Fayette County, Illinois
|
716.5
|
| 21 |
Knox County, Illinois
|
716.4
|
| 22 |
Madison County, Illinois
|
715.6
|
| 23 |
Wayne County, Illinois
|
713.8
|
| 24 |
Christian County, Illinois
|
709.4
|
| 25 |
Montgomery County, Illinois
|
703.7
|
| 26 |
Whiteside County, Illinois
|
684.2
|
| 27 |
Kankakee County, Illinois
|
676.6
|
| 28 |
St Clair County, Illinois
|
657.8
|
| 29 |
Tazewell County, Illinois
|
649.0
|
| 30 |
DeKalb County, Illinois
|
631.3
|
| 31 |
Edgar County, Illinois
|
623.4
|
| 32 |
Peoria County, Illinois
|
619.2
|
| 33 |
Logan County, Illinois
|
618.1
|
| 34 |
McHenry County, Illinois
|
603.2
|
| 35 |
Jo Daviess County, Illinois
|
601.1
|
| 36 |
McDonough County, Illinois
|
589.4
|
| 37 |
Jackson County, Illinois
|
584.1
|
| 38 |
Macon County, Illinois
|
580.7
|
| 39 |
Randolph County, Illinois
|
575.5
|
| 40 |
Marion County, Illinois
|
572.4
|
| 41 |
Jefferson County, Illinois
|
571.2
|
| 42 |
Morgan County, Illinois
|
568.8
|
| 43 |
Stephenson County, Illinois
|
564.5
|
| 44 |
Washington County, Illinois
|
562.6
|
| 45 |
Mercer County, Illinois
|
561.2
|
| 46 |
Greene County, Illinois
|
543.0
|
| 47 |
Warren County, Illinois
|
542.4
|
| 48 |
Mason County, Illinois
|
539.2
|
| 49 |
Woodford County, Illinois
|
527.8
|
| 50 |
Kane County, Illinois
|
520.1
|
| 51 |
Winnebago County, Illinois
|
513.4
|
| 52 |
Coles County, Illinois
|
508.3
|
| 53 |
Clark County, Illinois
|
501.4
|
| 54 |
White County, Illinois
|
494.8
|
| 55 |
Jasper County, Illinois
|
494.5
|
| 56 |
Ford County, Illinois
|
485.6
|
| 57 |
Effingham County, Illinois
|
478.8
|
| 58 |
Clinton County, Illinois
|
474.1
|
| 59 |
Clay County, Illinois
|
468.3
|
| 60 |
Carroll County, Illinois
|
444.8
|
| 61 |
Lake County, Illinois
|
443.7
|
| 62 |
Crawford County, Illinois
|
443.6
|
| 63 |
Perry County, Illinois
|
441.8
|
| 64 |
Piatt County, Illinois
|
439.2
|
| 65 |
Schuyler County, Illinois
|
437.3
|
| 66 |
Hamilton County, Illinois
|
434.7
|
| 67 |
Rock Island County, Illinois
|
427.6
|
| 68 |
Williamson County, Illinois
|
420.1
|
| 69 |
Grundy County, Illinois
|
418.0
|
| 70 |
Douglas County, Illinois
|
416.7
|
| 71 |
Union County, Illinois
|
413.5
|
| 72 |
Franklin County, Illinois
|
408.9
|
| 73 |
De Witt County, Illinois
|
397.5
|
| 74 |
Marshall County, Illinois
|
386.8
|
| 75 |
Monroe County, Illinois
|
385.0
|
| 76 |
Bond County, Illinois
|
380.3
|
| 77 |
Saline County, Illinois
|
379.8
|
| 78 |
Henderson County, Illinois
|
378.9
|
| 79 |
Cass County, Illinois
|
375.8
|
| 80 |
Lawrence County, Illinois
|
372.2
|
| 81 |
Jersey County, Illinois
|
369.3
|
| 82 |
Pope County, Illinois
|
368.8
|
| 83 |
Richland County, Illinois
|
360.0
|
| 84 |
Cumberland County, Illinois
|
346.0
|
| 85 |
Johnson County, Illinois
|
343.9
|
| 86 |
Moultrie County, Illinois
|
335.9
|
| 87 |
DuPage County, Illinois
|
327.5
|
| 88 |
Gallatin County, Illinois
|
323.1
|
| 89 |
Kendall County, Illinois
|
320.3
|
| 90 |
Menard County, Illinois
|
314.4
|
| 91 |
Brown County, Illinois
|
305.6
|
| 92 |
Stark County, Illinois
|
288.1
|
| 93 |
Boone County, Illinois
|
280.7
|
| 94 |
Calhoun County, Illinois
|
253.8
|
| 95 |
Scott County, Illinois
|
250.9
|
| 96 |
Massac County, Illinois
|
237.2
|
| 97 |
Alexander County, Illinois
|
235.5
|
| 98 |
Wabash County, Illinois
|
223.2
|
| 99 |
Edwards County, Illinois
|
222.4
|
| 100 |
Pulaski County, Illinois
|
199.2
|
| 101 |
Hardin County, Illinois
|
177.5
|
| 102 |
Putnam County, Illinois
|
160.2
|