Colorado Counties by Population (2025)

Top 5 Most Populous Counties

Colorado flag El Paso County

751,453

Colorado flag Denver County

722,825

Colorado flag Arapahoe County

655,645

Colorado flag Jefferson County

577,476

Colorado flag Adams County

545,077

64 counties

County
2025 Pop. ↓
Area (mi²)
Density
Change (2020)
El Paso County751,4532,1263532.6%
Denver County722,8251534,7240.73%
Arapahoe County655,6457988220.06%
Jefferson County577,476764756-0.96%
Adams County545,0771,1674674.72%
Douglas County399,84484147510.97%
Weld County377,7943,9859513.98%
Larimer County377,1592,5961454.79%
Boulder County325,815726449-1.55%
Pueblo County169,3222,387710.59%
Mesa County161,9813,329493.83%
Broomfield County78,190332,3694.97%
Garfield County63,6092,947222.94%
La Plata County56,1151,690330.79%
Eagle County52,7071,68431-5.3%
Fremont County51,7221,534345.82%
Montrose County44,8542,241204.76%
Delta County32,1181,142283.42%
Elbert County30,7341,8501717.23%
Summit County30,12360850-2.83%
Morgan County30,0401,280233.32%
Montezuma County26,6592,029132.98%
Routt County25,0482,362110.87%
Teller County24,13155743-2.48%
Chaffee County21,3211,013219.43%
Logan County20,2731,83911-4.42%
Park County18,5092,19486.26%
Otero County17,7861,26214-4.7%
Gunnison County17,3233,23952.2%
Alamosa County16,791723232.53%
Grand County16,3371,84693.75%
Pitkin County16,22697117-6.51%
Archuleta County14,5891,350118.68%
Las Animas County14,4224,7733-0.47%
Moffat County13,5714,74332.28%
Prowers County11,5071,6387-4.24%
Rio Grande County10,89091212-5.64%
Yuma County9,7962,3644-1.76%
Clear Creek County8,70739522-7.3%
San Miguel County7,5881,2876-5.79%
Lake County7,40337720-0.07%
Conejos County7,3891,2876-0.83%
Kit Carson County7,0162,1613-0.65%
Huerfano County6,9711,59142.11%
Saguache County6,8103,16926.59%
Rio Blanco County6,6093,22121.37%
Bent County6,1651,513412.64%
Gilpin County6,006150403.2%
Custer County5,928739825.51%
Crowley County5,6547877-0.6%
Lincoln County5,4202,5782-4.27%
Ouray County5,322541109.01%
Washington County4,8712,51821.21%
Phillips County4,53268870.11%
Costilla County3,6541,22834.34%
Baca County3,1622,5551-9.14%
Dolores County2,6191,067212.36%
Sedgwick County2,3255484-2.68%
Cheyenne County1,7191,7781-1.55%
Jackson County1,2991,6141-5.8%
Kiowa County1,2841,7681-11.75%
Mineral County970876110.98%
San Juan County794388211.67%
Hinsdale County7531,1171-4.44%

Overview of Colorado Counties

There are 64 counties in Colorado.

The most populous county in Colorado in 2019 is Denver County, home of Denver, with a population of 704,621. This represents significant population growth of 16.81% since the 2010 census.

Colorado is home to several other counties exceeding 500,000 residents:

All of these counties have experienced population growth of at least 7%, but none exceeded Denver County’s growth rate.

Colorado Counties with Fewest Residents

The smallest county in Colorado in terms of population is San Juan County, with just 715 people, up 0.99% from the last census. There are two other counties in Colorado with populations under 800:

Colorado has a total of 26 counties with populations under 10,000. Other small counties include:

Colorado Counties with Rapid Growth

Broomfield County, Colorado experienced the most significant population growth in the state since the census, growing by 21.57%. Other counties with rapid growth rates include:

The county that has experienced the most extreme negative growth is Kit Carson County, with a growth rate of -13.38%, bringing its population down to 7,158.

Sources

  1. US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
  2. US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
  3. American Community Survey (2009 - 2013)
  4. Census QuickFacts
  5. Historical Populations of States and Counties (1790 - 1990)