• county
  • FIPS 16001
  • Largest town: Boise City

Ada County, Idaho

Ada County had 535,799 residents in the Census Vintage 2024 estimate, on 1,052.2 square miles of land. It is the most populous of Idaho's 44 county-equivalents.

Population
535,799
#1 of 44 in Idaho · #138 in US
Area
1,052.2 sq mi
#31 of 44 in Idaho · #621 in US
Density
509 / sq mi
#1 of 44 in Idaho · #277 in US
Median household income
$90,513
#3 of 44 in Idaho · #236 in US

Census Vintage 2024 estimates · SAIPE 2023 income · 2024 Gazetteer land area

Ada County within Idaho. Pin: Boise.

Measure from here

Tools and pages that start from Ada County

Ada County population, land area and income

Ada County had 535,799 residents in the Census Vintage 2024 estimate, on 1,052.2 square miles of land. It is the most populous of Idaho's 44 county-equivalents. That works out to 509.2 people per square mile, 5.3 times the US average of 96.3, and in the top tenth nationally.

The median county-equivalent in Idaho has 15,019 residents, so Ada County is 35.7 times that size.

Its SAIPE 2023 median household income of $90,513 is in the top tenth among 3,143 counties with an estimate.

National rank among 3,144

Population

535,799

3144th1st

138th of 3,144 (US)

Land area

1,052 sq mi

3144th1st

621st of 3,144 (US)

Density

509.2 / sq mi

3144th1st

277th of 3,144 (US)

Median household income

$90,513

3143rd1st

236th of 3,143 (US)

Rank within Idaho (44)

Population

535,799

44th1st

1st of 44 (ID)

Land area

1,052 sq mi

44th1st

31st of 44 (ID)

Density

509.2 / sq mi

44th1st

1st of 44 (ID)

Median household income

$90,513

44th1st

3rd of 44 (ID)

How Ada County's population changed since 2020

Ada County gained 37,498 residents between the July 2020 and July 2024 estimates, a rise of 7.5%. That ranks 20th of 44 in Idaho for growth. The median Idaho county changed by +7.2%, and the state as a whole by +8.2%.

Since the April 2020 estimates base, Ada County recorded 21,330 births and 16,604 deaths, a natural change of +4,726. Net international migration added +6,584 and net domestic migration, people moving to or from other US counties, came to +30,239. The largest single component was domestic migration, which added 30,239 people.

498.3k2020513.1k2021520.8k2022526.7k2023535.8k2024
Census Vintage 2024 county estimates for July 1 of each year. The axis starts above zero so year-to-year changes are visible.

Components of change, April 2020 to July 2024

Births
21,330
Deaths
16,604
Net international migration
+6,584
Net domestic migration
+30,239
Change, July 2023 to July 2024
+9,109

Where Ada County is

The Census internal point of Ada County is at 43.451500, -116.244400. It sits in UTM zone 11N. The map shades Idaho's 44 county-equivalents by population change from 2020 to 2024, darker for faster growth, with Ada County outlined. Dots are towns of 1,000+ people with residents in it.

Madison County: +5.0%Idaho County: +8.0%Benewah County: +9.9%Gooding County: +3.4%Lincoln County: +8.2%Minidoka County: +4.7%Custer County: +7.7%Boundary County: +15.6%Lemhi County: +5.5%Twin Falls County: +6.8%Franklin County: +9.5%Oneida County: +9.0%Gem County: +13.4%Shoshone County: +6.6%Fremont County: +7.3%Clearwater County: +4.6%Kootenai County: +9.0%Cassia County: +4.9%Blaine County: +3.8%Clark County: +0.1%Jerome County: +7.4%Bonner County: +13.8%Elmore County: +3.7%Caribou County: +3.2%Bonneville County: +7.1%Jefferson County: +12.1%Power County: +6.3%Lewis County: +5.8%Nez Perce County: +1.7%Ada County: +7.5%Adams County: +12.9%Valley County: +7.9%Bingham County: +5.8%Bannock County: +4.3%Owyhee County: +6.2%Washington County: +9.3%Latah County: +6.4%Teton County: +10.2%Camas County: +15.0%Boise County: +12.0%Bear Lake County: +6.5%Butte County: +5.9%Canyon County: +14.5%Payette County: +8.1%
Change 2020 to 2024
  1. < +4.7%
  2. < +6.4%
  3. < +7.7%
  4. < +9.9%
  5. ≥ +9.9%
no data

Orange pin: Ada County internal point. Dark pin: Boise.

Internal point

Decimal
43.451500, -116.244400
DMS
43°27'5.40"N 116°14'39.84"W
UTM
11N 561134.9E 4811232.3N
Geohash
9rtr4y17m
Plus code
85M5FQ24+J6

Towns in Ada County

6 incorporated places of 1,000+ people have residents in Ada County, 471,372 people together, or 88% of the county. Each figure counts only the part of the town inside Ada County; towns marked "part" extend into another county. The largest is Boise City with 237,963.

  1. 01Boise City237,963
  2. 02Meridian139,740
  3. 03Eagle33,451
  4. 04Kuna29,127
  5. 05Star (part)18,155
  6. 06Garden City12,936
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering Ada County

The Census 2024 county adjacency file lists 5 neighbors for Ada County. The most populous is Canyon County, ID, with 266,892 residents. Distances run between Census internal points in a straight line.

Distance to Boise and the nearest big city

Boise is 11.6 miles N of Ada County's internal point in a straight line. The nearest place of 100,000 or more is Boise City, ID (population 237,963), 10.3 miles away. The nearest place of 10,000 or more is Kuna, ID (population 29,127), 9.4 miles away.

Ada County FIPS code

The FIPS code of Ada County is 16001: state code 16 for Idaho plus county code 001. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $90,513.

Questions people ask

What is the population of Ada County, Idaho?

The Census Vintage 2024 estimate for July 1, 2024 is 535,799. That is up 37,498 people (7.5%) from the July 2020 estimate of 498,301.

What is the FIPS code of Ada County?

16001. The first two digits (16) are Idaho; the last three (001) identify the county.

What is the largest town in Ada County?

Boise City, with 237,963 residents inside Ada County in 2024.

Which counties border Ada County?

5 county-equivalents border it in the Census 2024 adjacency file: Canyon County, ID; Elmore County, ID; Gem County, ID; Owyhee County, ID; Boise County, ID.

Sources and data as of

Data as of: Census Vintage 2024 population estimates, 2024 Gazetteer land area and internal points, SAIPE 2023 median household income.

  1. 01Census Vintage 2024 county population estimates
  2. 02Census 2024 Gazetteer, counties
  3. 03Census SAIPE 2023 state and county estimates
  4. 04Census Vintage 2024 subcounty population estimates
  5. 05Census 2024 county adjacency file
  6. 06Census 2024 cartographic boundary file, counties (1:5,000,000)

How every number is computed: methodology. Spotted a wrong figure? Report an error.