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What are the fastest-growing counties in Illinois?

Kendall County (+9.9%), Grundy County (+2.9%) and Brown County (+2.7%) grew fastest in Illinois between 2020 and 2025.

Illinois as a whole shrank 0.6% between 2020 and 2025, to 12,719,141 residents.

Data as of 2025 · updated

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All 102 Illinois counties ranked

Illinois counties by population growth
RankCountyResidents 2025Change 2020–25Net migration per 1,000, 2025New homes per 1,000, 2025
1Kendall County145,470+9.9%8.85.0
2Grundy County54,052+2.9%5.22.1
3Brown County6,401+2.7%−4.21.1
4McHenry County317,751+2.5%4.74.4
5Will County712,253+2.2%0.32.8
6Kane County525,757+1.8%−0.73.1
7Champaign County209,972+1.8%−10.74.1
8DeKalb County101,835+1.5%8.42.6
9Lake County719,339+0.8%−4.42.0
10Piatt County16,791+0.6%10.82.3
11Bond County16,959+0.6%23.61.5
12Clinton County37,128+0.6%1.01.4
13Douglas County19,880+0.5%−3.31.4
14Boone County53,568+0.4%−0.11.3
15Johnson County13,363+0.3%4.00.0
16DuPage County934,298+0.3%−6.31.4
17Williamson County67,225+0.1%4.12.1
18McLean County171,419+0.1%−6.31.6
19Crawford County18,648+0.1%3.40.5
20Putnam County5,619−0.1%3.01.1
21Monroe County34,840−0.3%−2.51.9
22Winnebago County283,674−0.4%0.61.1
23Effingham County34,519−0.5%−1.61.4
24Randolph County29,921−0.6%3.10.2
25Montgomery County28,076−0.6%11.90.4
26Ogle County51,399−0.7%3.21.7
27Woodford County38,111−0.8%−2.81.0
28Moultrie County14,371−0.8%−5.12.0
29Tazewell County130,049−1.0%2.50.9
30Madison County263,110−1.0%1.21.7
31Coles County46,607−1.0%−0.30.3
32Sangamon County194,170−1.0%−0.51.2
33Stark County5,319−1.2%9.60.2
34Washington County13,564−1.2%0.01.1
35Cook County5,194,625−1.3%−6.01.0
36Jackson County52,501−1.5%−7.90.1
37LaSalle County107,773−1.5%1.10.6
38Christian County33,443−1.5%2.61.8
39Jersey County21,160−1.5%5.51.8
40Wayne County15,882−1.6%−0.30.1
41Peoria County178,553−1.6%−4.10.4
42Shelby County20,576−1.6%5.32.2
43Carroll County15,419−1.7%1.71.2
44Hamilton County7,859−1.7%2.5–
45Rock Island County141,869−1.7%−3.01.3
46Kankakee County105,525−1.7%−2.21.1
47Hardin County3,588−1.8%0.60.0
48Fulton County32,901−2.0%9.40.5
49Marshall County11,473−2.0%−3.40.3
50Franklin County36,916−2.1%3.00.5
51Adams County64,267−2.1%1.80.6
52Livingston County35,057−2.1%−0.51.4
53Bureau County32,510−2.1%3.10.5
54Cumberland County10,208−2.1%−4.70.0
55De Witt County15,118−2.1%−1.80.9
56Henry County48,095−2.2%−0.40.4
57Pope County3,672−2.2%−1.60.3
58Clark County15,114−2.2%3.20.6
59Ford County13,216−2.2%−4.01.1
60Jo Daviess County21,594−2.2%0.91.9
61Calhoun County4,300−2.3%−3.01.2
62Jefferson County36,147−2.3%2.90.3
63Jasper County9,032−2.4%4.00.7
64St. Clair County250,708−2.5%−1.61.8
65Logan County27,182−2.5%1.72.4
66Whiteside County54,121−2.6%−1.80.4
67Mercer County15,229−2.6%−0.91.2
68Macoupin County43,748−2.6%0.51.6
69Pike County14,231−2.8%−0.70.8
70Edgar County16,323−2.9%4.20.2
71Morgan County32,515−2.9%−0.20.5
72Stephenson County43,220−3.0%−0.40.3
73Iroquois County26,150−3.0%1.70.5
74Schuyler County6,657−3.0%−4.80.0
75Fayette County20,790−3.2%−4.60.1
76Menard County11,863−3.3%−1.80.9
77Lee County32,914−3.4%5.41.0
78Marion County36,382−3.4%0.10.3
79Perry County20,160−3.5%−7.51.1
80Clay County12,793−3.6%−1.20.2
81Wabash County10,907−3.6%−6.10.6
82Warren County16,222−3.7%5.10.2
83Vermilion County71,259−3.7%−0.20.1
84Union County16,656−3.7%−5.00.6
85Richland County15,219−3.7%−4.60.5
86Cass County12,463−4.0%−11.70.2
87Scott County4,866−4.0%−2.7–
88White County13,250−4.0%−6.90.1
89Saline County22,772−4.1%4.50.0
90Knox County47,767−4.1%−1.80.0
91Macon County99,300−4.3%−4.70.4
92Hancock County16,803−4.4%−3.70.1
93McDonough County25,916−4.5%−5.00.0
94Massac County13,502−4.5%1.90.6
95Mason County12,411−4.9%2.20.5
96Edwards County5,898−5.0%−11.2–
97Greene County11,313−5.1%−0.70.2
98Henderson County5,984−5.6%−3.50.7
99Gallatin County4,616−6.4%−2.6–
100Pulaski County4,820−6.9%−5.80.6
101Lawrence County13,790−9.7%6.84.9
102Alexander County4,570−11.6%0.40.0

Ranked by the change in Census Bureau population estimates, 2020–2025.

Statewide totals

More county rankings for Illinois

Metro areas

Fastest-growing metro areas in Illinois · Fastest-growing metro areas in the U.S. · Largest metro areas in Illinois

Every U.S. metro and micro area

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Questions

Is Illinois growing?

Illinois as a whole shrank 0.6% between 2020 and 2025, to 12,719,141 residents. Statewide figures add up its counties.

What is the fastest-growing county in Illinois?

Kendall County, which grew 9.9% between 2020 and 2025 to 145,470 residents (Census Bureau population estimates). Grundy County (+2.9%) and Brown County (+2.7%) came next.

Which Illinois counties are losing population?

83 of the 102 ranked counties had fewer residents in 2025 than in 2020. The steepest declines: Alexander County (−11.6%), Lawrence County (−9.7%), Pulaski County (−6.9%).

Where are people moving in Illinois?

For their size, Bond County (23.6 per 1,000 residents), Montgomery County (11.9 per 1,000 residents) and Piatt County (10.8 per 1,000 residents) drew the most net domestic migration (people moving in from other U.S. counties minus people moving out) in 2025.

Fastest-growing counties in other states

Across the U.S.

Sources and method

Each number shows its own period. Changes compare the latest period with five years earlier (or the earliest period available). Beacon CRE last refreshed these figures on 2026-11-05. Figures come from public federal statistics and are informational only, not investment advice. Check the source before relying on a number. Methodology: how we compute every number. More on every layer: data sources and licences.