Illinois Land area in square miles, 2010 by County

Data Item State
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Land area in square miles, 2010 - (Square Miles)
County Value
Adams 855.20
Alexander 235.51
Bond 380.28
Boone 280.72
Brown 305.61
Bureau 869.03
Calhoun 253.83
Carroll 444.81
Cass 375.82
Champaign 996.27
Christian 709.38
Clark 501.42
Clay 468.32
Clinton 474.09
Coles 508.29
Cook 945.33
Crawford 443.63
Cumberland 346.02
De Witt 397.51
DeKalb 631.31
Douglas 416.67
DuPage 327.50
Edgar 623.37
Edwards 222.42
Effingham 478.78
Fayette 716.48
Ford 485.62
Franklin 408.89
Fulton 865.60
Gallatin 323.07
Greene 543.02
Grundy 418.04
Hamilton 434.67
Hancock 793.73
Hardin 177.53
Henderson 378.87
Henry 822.99
Iroquois 1,117.32
Jackson 584.08
Jasper 494.51
Jefferson 571.17
Jersey 369.27
Jo Daviess 601.09
Johnson 343.92
Kane 520.06
Kankakee 676.56
Kendall 320.34
Knox 716.40
Lake 443.67
LaSalle 1,135.12
Lawrence 372.18
Lee 724.90
Livingston 1,044.29
Logan 618.06
Macon 580.69
Macoupin 862.91
Madison 715.58
Marion 572.36
Marshall 386.79
Mason 539.24
Massac 237.22
McDonough 589.41
McHenry 603.17
McLean 1,183.38
Menard 314.44
Mercer 561.20
Monroe 385.01
Montgomery 703.69
Morgan 568.79
Moultrie 335.94
Ogle 758.57
Peoria 619.21
Perry 441.76
Piatt 439.20
Pike 831.38
Pope 368.77
Pulaski 199.19
Putnam 160.16
Randolph 575.50
Richland 359.99
Rock Island 427.64
Saline 379.82
Sangamon 868.30
Schuyler 437.27
Scott 250.91
Shelby 758.52
St. Clair 657.76
Stark 288.08
Stephenson 564.52
Tazewell 648.97
Union 413.46
Vermilion 898.37
Wabash 223.25
Warren 542.41
Washington 562.57
Wayne 713.81
White 494.77
Whiteside 684.25
Will 836.91
Williamson 420.15
Winnebago 513.36
Woodford 527.80

Value for Illinois (Square Miles): 55,518.93

Source: U.S. Census Bureau, data file from Geography Division based on the TIGER/Geographic Identification Code Scheme (TIGER/GICS) computer file. Land area updated every 10 years. or

Source: U.S. Census Bureau, Census of Population and Housing. Land area is based on current information in the TIGER® data base, calculated for use with Census 2010.


Land area is the size, in square units (metric and nonmetric) of all areas designated as land in the Census Bureau's national geographic (TIGER®) database.

Persons per square mile is the average number of inhabitants per square mile of land area. These figures are derived by dividing the total number of residents by the number of square miles of land area in the specified geographic area. The land area measurement is from the Census 2010. To determine population per square kilometer, multiply the population per square mile by .3861.

Scope and Methodology:

TIGER is an acronym for the digital (computer-readable) geographic database that automates the mapping and related geographic activities required to support the Census Bureau's census and survey programs. The Census Bureau developed the Topologically Integrated Geographic Encoding and Referencing (TIGER) System to automate the geographic support processes needed to meet the major geographic needs of the 1990 census. Land area was calculated from the specific set of boundaries recorded for the entity (in this case, counties, which were then aggregated to metropolitan totals) in the Census Bureau's geographic database.

Land area measurements are originally recorded as whole square meters (to convert square meters to square kilometers, divide by 1,000,000; to convert square kilometers to square miles, divide by 2.58999; to convert square meters to square miles, divide by 2,589,988).

Land area measurements may disagree with the information displayed on U.S. Census Bureau maps and in the TIGER® database because, for area measurement purposes, features identified as "intermittent water" and "glacier" are reported as land area.

The accuracy of any area measurement data is limited by the accuracy inherent in (1) the location and shape of the various boundary information in the TIGER® database and (2) rounding affecting the last digit in all operations that compute and/or sum the area measurements. Identification of land is for statistical purposes and does not necessarily reflect legal definitions.

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