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What are the largest counties in Colorado?

El Paso County is the largest county in Colorado, with 757,040 residents in 2025 (Census PEP). Denver County (740,613) and Arapahoe County (673,820) come next.

Data as of 2025 · updated

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All 61 ranked Colorado counties

Colorado counties ranked by population
RankCountyResidents 2025Change 2020–25
1El Paso County757,040+3.2%
2Denver County740,613+3.2%
3Arapahoe County673,820+2.8%
4Jefferson County580,451−0.5%
5Adams County554,668+6.6%
6Douglas County399,396+10.8%
7Weld County378,426+14.2%
8Larimer County377,292+4.8%
9Boulder County328,560−0.7%
10Pueblo County169,277+0.6%
11Mesa County162,845+4.4%
12Broomfield County79,174+6.3%
13Garfield County63,474+2.7%
14La Plata County56,898+2.2%
15Eagle County54,291−2.5%
16Fremont County50,039+2.4%
17Montrose County44,591+4.1%
18Delta County32,178+3.6%
19Summit County31,517+0.9%
20Elbert County30,534+16.5%
21Morgan County30,306+4.2%
22Montezuma County26,678+3.0%
23Routt County25,329+2.0%
24Teller County24,756+0.0%
25Chaffee County20,831+6.9%
26Logan County20,654−2.7%
27Park County18,314+5.1%
28Otero County17,683−5.2%
29Gunnison County17,439+2.9%
30Alamosa County16,688+1.9%
31Pitkin County16,625−4.3%
32Grand County16,496+4.7%
33Las Animas County14,391−0.7%
34Archuleta County14,306+6.6%
35Moffat County13,122−1.1%
36Prowers County11,884−1.1%
37Rio Grande County11,087−3.9%
38Yuma County9,896−0.8%
39Clear Creek County8,994−3.9%
40San Miguel County7,753−3.7%
41Lake County7,552+1.9%
42Conejos County7,529+1.0%
43Kit Carson County7,069+0.1%
44Huerfano County7,011+2.7%
45Saguache County6,732+5.3%
46Rio Blanco County6,683+2.5%
47Gilpin County6,073+4.4%
48Bent County5,716+4.5%
49Crowley County5,677−0.5%
50Lincoln County5,645−0.4%
51Custer County5,590+18.3%
52Ouray County5,265+7.9%
53Washington County4,732−1.6%
54Phillips County4,420−2.4%
55Costilla County3,679+5.1%
56Baca County3,347−3.8%
57Dolores County2,466+5.8%
58Sedgwick County2,247−6.0%
59Cheyenne County1,713−1.9%
60Kiowa County1,412−2.8%
61Jackson County1,211−12.2%

How this is ranked

The Census Bureau's July 1 resident population estimates for 2025, largest first, with the change since 2020. Counties with fewer than 1,000 residents are not ranked. Areas without an estimate for the same year as the others are not ranked.

Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025). Figures come from public federal statistics and are informational only, not investment advice. Check the source before relying on a number. Methodology: how ranks and figures are built.

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Questions

What is the largest county in Colorado?

El Paso County is the largest county in Colorado, with 757,040 residents in 2025 (Census PEP). Denver County (740,613) and Arapahoe County (673,820) come next.

How is this ranking calculated?

The Census Bureau's July 1 resident population estimates for 2025, largest first, with the change since 2020. Counties with fewer than 1,000 residents are not ranked. Areas without an estimate for the same year as the others are not ranked.

More rankings for Colorado

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