Population of Counties in Colorado (2020)

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 including El Paso County (699,232), Arapahoe County (643,052), Jefferson County (574,613), and Adams County (503,167). All of these counties have experienced population growth of at least 7% but not exceeding Denver County's growth.

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: Mineral County (766) and Hinsdale County (794). Colorado has a total of 26 counties under 10,000 residents. Other small Colorado counties include Kiowa County (1,376), Jackson County (1,385), Cheyenne County (1,845), Dolores County (2,067), and Sedgwick County (2,344). The most significant growth among these counties was Mineral County at 8.81%. Hinsdale County experienced the most dramatic decline with a growth rate of -5.92%.

Colorado Counties with Rapid Growth

Broomsfield 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 Weld County (19.85%), Douglas County (16.85%), Denver County (16.81%), and Larimer County (14.50%). The county that has experienced the most extreme negative growth is Kit Carson County with a growth rate of -13.38% which has brought its population down to 7,158.

Name 2020 Population Growth Since 2010
Denver County716,49218.75%
El Paso County713,85613.87%
Arapahoe County651,21513.30%
Jefferson County580,2338.29%
Adams County511,86815.36%
Larimer County350,51816.66%
Douglas County342,77619.44%
Boulder County326,07810.25%
Weld County314,30523.65%
Pueblo County167,5295.06%
Mesa County153,2074.68%
Broomfield County69,26723.20%
Garfield County59,7706.56%
La Plata County56,3109.67%
Eagle County54,9935.54%
Fremont County48,0212.53%
Montrose County42,2142.50%
Summit County31,00710.44%
Delta County30,9530.30%
Morgan County28,5581.12%
Elbert County26,28213.56%
Montezuma County26,1582.27%
Routt County25,7339.74%
Teller County25,0836.88%
Logan County21,528-2.29%
Chaffee County20,02712.46%
Park County18,55613.98%
Otero County18,432-2.41%
Pitkin County17,9504.60%
Gunnison County17,24612.32%
Alamosa County16,6834.71%
Grand County15,5254.93%
Las Animas County14,503-5.90%
Archuleta County13,76514.27%
Moffat County13,188-4.39%
Prowers County12,164-3.27%
Rio Grande County11,250-6.43%
Yuma County10,020-0.29%
Clear Creek County9,6055.86%
Conejos County8,200-1.35%
San Miguel County8,19111.34%
Lake County7,8247.71%
Kit Carson County7,163-13.31%
Huerfano County6,8893.13%
Saguache County6,84311.52%
Rio Blanco County6,336-5.08%
Gilpin County6,12111.80%
Bent County5,882-9.51%
Crowley County5,858-0.05%
Lincoln County5,6102.54%
Custer County4,95415.67%
Washington County4,9091.83%
Ouray County4,8338.46%
Phillips County4,286-4.12%
Costilla County3,8288.47%
Baca County3,585-5.83%
Sedgwick County2,303-2.87%
Dolores County2,0740.24%
Cheyenne County1,8762.35%
Jackson County1,3990.72%
Kiowa County1,383-1.50%
Hinsdale County811-3.91%
Mineral County77610.23%
San Juan County7627.63%