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Population of Counties in Idaho (2024)

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2024 Population
Growth Since 2020
Area (mi²)
Density (/mi²)
Ada County530,3426.43%406504Ada County location
Canyon County264,45613.49%227451Canyon County location
Kootenai County186,7308.07%478151Kootenai County location
Bonneville County133,1896.78%72071Bonneville County location
Twin Falls County96,4916.77%74250Twin Falls County location
Bannock County91,1754.47%42982Bannock County location
Madison County54,1362.28%181115Madison County location
Bonner County53,68713.26%66931Bonner County location
Bingham County50,8175.66%80824Bingham County location
Nez Perce County43,0652.18%32751Nez Perce County location
Latah County41,6785.15%41539Latah County location
Jefferson County35,06012.81%42232Jefferson County location
Elmore County30,0574.84%1.2K10Elmore County location
Payette County27,6297.97%15768Payette County location
Cassia County25,7483.99%99010Cassia County location
Jerome County25,7145.95%23143Jerome County location
Blaine County25,1813.42%1K10Blaine County location
Minidoka County22,7525%29230Minidoka County location
Gem County21,68812.54%21639Gem County location
Idaho County18,1439.33%3.3K2Idaho County location
Gooding County16,2433.8%28122Gooding County location
Franklin County15,81810.75%25624Franklin County location
Fremont County14,3757.12%7208Fremont County location
Shoshone County14,1176.96%1K5Shoshone County location
Boundary County13,84214.03%49011Boundary County location
Valley County12,8388.41%1.4K4Valley County location
Owyhee County12,7996.69%3K2Owyhee County location
Teton County12,5797.19%17328Teton County location
Washington County11,70310.84%5618Washington County location
Benewah County10,4479.1%30013Benewah County location
Clearwater County9,3937.35%9484Clearwater County location
Boise County8,67413.18%7335Boise County location
Lemhi County8,5987.99%1.8K2Lemhi County location
Power County8,3706.23%5426Power County location
Caribou County7,2383.21%6814Caribou County location
Bear Lake County6,8026.83%3777Bear Lake County location
Lincoln County5,5157.42%4645Lincoln County location
Oneida County5,16613.14%4634Oneida County location
Adams County5,01513.26%5264Adams County location
Custer County4,5286.02%1.9K1Custer County location
Lewis County3,7536.41%1858Lewis County location
Butte County2,8189.06%8631Butte County location
Camas County1,29519.46%4151Camas County location
Clark County7920%6810.45Clark County location
showing: 44 rows

There are 44 counties in Idaho. As of 2019, Idaho's most populous county is Ada County, home of Boise, with 469,966 residents. This represents a population growth of 19.48% since the 2010 census. Ada County is followed by Canyon County (223,499), Kootenai County (161,505), and Bonneville County (116,854). These are the only counties in Idaho with a population exceeding 100,000. Of these counties, Ada County experienced the highest population growth.

Idaho Counties with Fewest Residents

The least populated county in Idaho is Clark County with a population of 852 in 2019, down 13.06% since the last census. There are 15 counties in Idaho with fewer than 10,000 residents. Other small counties in Idaho are Camas County (1,127), Butte County (2,611), Lewis County (3,861), Adams County (4,250), Custer County (4,280), and Oneida County (4,488). Of these counties, Clark County experienced the most dramatic decline with a population growth rate of -13.06%. Adams County experienced the highest growth with a population that grew by 7.27% since the census.

Idaho Counties with Rapid Growth

Ada County, the largest county in Idaho, also experienced the most rapid growth over the last decade, climbing 19.48% to 469,966 people. Other cities that have experienced rapid growth include Canyon County (18.03%), Kootenai County (16.31%), Teton County (14.67%), Valley County (12.80%), and Jefferson County (12.27%). Only 8 counties in Idaho experienced negative growth since the census. The most dramatic decline was in Clark County, which dropped 13.06%, followed by Butte County at -10.43%. No other county experienced decline of more than 2%.

Lists of Counties in all States

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