Population of Counties in Illinois (2022)

There are 102 counties in Illinois.

In 2019, the most highly populated county within the state of Illinois is Cook County, home to the city of Chicago. With a population of 5,180,493, Cook County has seen a decrease in the total population of 0.36% since the last U.S. census was taken in 2010. Following Cook County, other large counties in Illinois are DuPage County (928,589), Lake County (700,832), Will County (692,310), and Kane County (534,216). Kane County reported the most significant population growth, increasing its population by 3.50%.

Illinois Counties with the Fewest Residents

The county with the lowest population in the state of Illinois is Hardin County, which has a population of 3,910. Since the last census in 2010, Hardin County’s population has seen a decrease of 9.35%. Following behind Hardin County, other small counties in Illinois include Pope County (4,212), Calhoun County (4,802), and Scott County (4,926). Illinois has 72 counties with a population of less than 50,000; all but one (Monroe County) experienced a decline in population. Of the 15 counties with fewer than 10,000 residents, Alexander County experienced the most dramatic decrease with a growth rate of -26.15%.

Illinois Counties with Rapid Growth

Kendall County is the fastest-growing county in Illinois with a population growth rate of 10.87% to 127,915 residents. Following Kendall County, Champagne County (4.19%), Monroe County (4.05%), and Kane County (3.5%) also experienced an increase in residents. Only five other counties in Illinois had any increase in population since 2010. The county with the lowest growth rate in Illinois is Alexander County, which has seen a population decrease of 26.15%.

Name 2022 Population Growth Since 2010 Density (mi²)
Adams County64,871-3.41%75.85
Alexander County4,921-40.03%20.89
Bond County15,793-11.21%41.53
Boone County53,736-0.67%191.41
Brown County6,623-4.28%21.67
Bureau County31,635-9.51%36.40
Calhoun County4,469-12.30%17.61
Carroll County14,278-7.25%32.08
Cass County11,652-14.53%31.00
Champaign County209,0023.70%209.79
Christian County31,257-10.09%44.06
Clark County14,964-8.15%29.84
Clay County12,938-6.42%27.63
Clinton County37,157-1.81%78.38
Coles County49,997-7.18%98.36
Cook County5,085,050-2.19%5,379.11
Crawford County18,178-8.20%40.98
Cumberland County10,652-3.63%30.78
DeKalb County106,5411.33%168.75
De Witt County15,170-8.56%38.16
Douglas County19,486-2.49%46.77
DuPage County909,943-0.88%2,778.33
Edgar County16,564-10.50%26.57
Edwards County6,419-4.68%28.86
Effingham County33,489-2.15%69.95
Fayette County21,240-4.03%29.64
Ford County12,208-13.30%25.14
Franklin County37,791-5.61%92.42
Fulton County32,870-11.34%37.97
Gallatin County4,177-25.05%12.93
Greene County12,681-8.70%23.35
Grundy County51,2972.28%122.70
Hamilton County8,020-5.04%18.45
Hancock County17,348-9.13%21.86
Hardin County3,605-16.53%20.31
Henderson County6,493-11.58%17.14
Henry County48,445-3.98%58.86
Iroquois County26,004-12.45%23.27
Jackson County55,133-8.68%94.39
Jasper County9,568-1.61%19.35
Jefferson County37,612-2.95%65.85
Jersey County21,707-5.60%58.78
Jo Daviess County20,947-7.51%34.86
Johnson County12,399-1.63%36.05
Kane County531,4522.98%1,021.70
Kankakee County109,589-3.38%161.98
Kendall County132,80915.11%414.66
Knox County48,862-7.65%68.20
Lake County687,379-2.38%1,549.33
LaSalle County107,199-5.82%94.44
Lawrence County15,273-9.84%41.04
Lee County33,496-6.91%46.21
Livingston County35,450-8.76%33.95
Logan County27,736-8.41%44.88
McDonough County28,776-11.82%48.82
McHenry County306,343-0.90%507.85
McLean County168,838-0.57%142.68
Macon County102,524-7.46%176.56
Macoupin County43,750-8.47%50.70
Madison County259,786-3.54%362.96
Marion County36,677-6.95%64.08
Marshall County11,303-10.56%29.22
Mason County12,837-12.38%23.81
Massac County13,019-15.35%54.88
Menard County11,917-6.14%37.90
Mercer County15,095-8.01%26.90
Monroe County35,4297.38%92.02
Montgomery County27,583-8.35%39.20
Morgan County32,551-8.31%57.23
Moultrie County14,060-5.38%41.85
Ogle County50,229-5.96%66.21
Peoria County174,856-6.10%282.39
Perry County20,232-9.33%45.80
Piatt County16,278-2.58%37.07
Pike County15,459-5.70%18.59
Pope County4,156-7.11%11.27
Pulaski County5,038-17.76%25.29
Putnam County5,748-4.39%35.89
Randolph County30,597-8.57%53.17
Richland County14,967-7.58%41.57
Rock Island County139,653-5.39%326.70
St. Clair County254,664-5.80%387.15
Saline County22,597-9.26%59.49
Sangamon County191,771-3.03%220.86
Schuyler County6,462-14.24%14.78
Scott County5,023-5.71%20.02
Shelby County21,358-4.46%28.16
Stark County5,114-14.32%17.75
Stephenson County43,601-8.41%77.23
Tazewell County129,862-4.15%200.07
Union County16,116-9.11%38.98
Vermilion County72,926-10.67%81.18
Wabash County11,511-3.40%51.56
Warren County16,400-7.41%30.24
Washington County13,551-7.89%24.09
Wayne County15,882-5.11%22.25
White County13,294-8.93%26.87
Whiteside County54,041-7.60%78.98
Will County689,5251.58%823.87
Williamson County65,442-1.49%155.75
Winnebago County279,398-5.32%544.19
Woodford County38,255-1.05%72.48