Ada County, Idaho

{{short description|County in Idaho, United States}} {{Use American English|date=June 2025}} {{Use mdy dates|date=April 2024}} {{Infobox U.S. county | county = Ada County | state = Idaho | ex image = James A. McClure Federal Bldg & U.S. Courthouse.JPG | ex image size = 220px | ex image cap = James A. McClure Federal Building and U.S. Courthouse in Boise, Idaho | flag = | seal = Adacountyseal.png | founded date = December 22 | founded year = 1864 | seat wl = Boise | largest city wl = Boise | area_total_sq_mi = 1060 | area_land_sq_mi = 1052.2 | area_water_sq_mi = 7.9 | area percentage = 0.7 | population_as_of = 2020 | population_total = 494967 | pop_est_as_of = 2025 | population_est = 546141 {{increase}} | population_density_sq_mi = auto | time zone = Mountain | district = 1st | district2 = 2nd | footnotes = County Code: 1A | web = https://adacounty.id.gov/ | named for = Ada Riggs |area_total_km2=2745|area_land_km2=2725|area_water_km2=20}} '''Ada County''' is located in the southwestern part of Idaho, United States. As of the 2020 census, the county had a population of 494,967,<ref name="QF">{{cite web|title=State & County QuickFacts|url=https://www.census.gov/quickfacts/fact/table/adacountyidaho/PST045222|publisher=United States Census Bureau|access-date=January 15, 2024}}</ref> which by 2025 was estimated to have risen to 546,141.<ref name="USCensusEst2024">{{cite web|url=https://www.census.gov/data/tables/time-series/demo/popest/2020s-counties-total.html|title=County Population Totals and Components of Change: 2020-2024|publisher=United States Census Bureau|access-date=May 17, 2025}}</ref> Ada County is by far the state's most populous county; it is home to 26.8% of the state's population. The county seat and largest city is Boise,<ref>{{cite web|url=http://www.naco.org/Counties/Pages/FindACounty.aspx|access-date=June 7, 2011|title=Find a County|publisher=National Association of Counties|url-status=dead|archive-url=https://web.archive.org/web/20110531210815/http://www.naco.org/Counties/Pages/FindACounty.aspx|archive-date=May 31, 2011}}</ref> which is also the state capital.<ref>{{cite web|url=http://www.visitidaho.org/facts-about-idaho/|title=Facts About Idaho|access-date=November 10, 2011|publisher=Idaho Department of Commerce|year=2011|url-status=dead|archive-url=https://web.archive.org/web/20110903042128/http://www.visitidaho.org/facts-about-idaho/|archive-date=September 3, 2011}}</ref> Ada County is included in the Boise metropolitan area. The Ada County Highway District has jurisdiction over all the local county and city streets, except for private roads and state roads. In the interior Pacific Northwest east of the Cascade Range, Ada County ranks second in population, behind Spokane County, Washington.

==History== Ada County was created by the Idaho Territory legislature on December 22, 1864, partitioned from Boise County. It is named for Ada Riggs, the daughter of H. C. Riggs, a member of the legislature; he established the county and was a co-founder of Boise.<ref>{{cite web|url=https://www.idaho.gov/counties/ada/|title=Ada County|access-date=August 28, 2017}}</ref> Canyon County, which originally included Payette County and most of Gem County, was partitioned from western Ada County in 1891.

==Geography== According to the United States Census Bureau, the county has a total area of {{convert|1060|sqmi}}, of which {{convert|1053|sqmi}} is land and {{convert|7.9|sqmi}} (0.7%) is water.<ref>{{cite web|url=https://www.census.gov/geographies/reference-files/time-series/geo/gazetteer-files.html|publisher=US Census Bureau|access-date=April 23, 2011|date=February 12, 2011|title=US Gazetteer files: 2010, 2000, and 1990}}</ref> The Boise River flows through the northern portion of the county, and the northwest border is bounded by the foothills of the Boise Range mountains; the summits are in adjacent Boise County. The southwestern border of the county is bounded by the Snake River.

===Adjacent counties=== {{div col}} * Gem County - northwest * Boise County - northeast * Elmore County - east * Owyhee County - south * Canyon County - west {{div col end}}

===Major highways=== {{div col}} * x25px - Interstate 84 * x25px - Interstate 184 * x25px - US 20 * x25px - US 26 * x25px - US 30 * x25px - SH-16 * x25px - SH-21 - ''Ponderosa Pine Scenic Byway'' * x25px - SH-44 * x25px - SH-55 - ''Payette River Scenic Byway'' * x25px - SH-69 {{div col end}}

County roads and highways are maintained by the Ada County Highway District.

===National protected areas=== * Boise National Forest (part) * Snake River Birds of Prey National Conservation Area (part)

==Demographics== {{US Census population |1870= 2675 |1880= 4674 |1890= 8368 |1900= 11559 |1910= 29088 |1920= 35213 |1930= 37925 |1940= 50401 |1950= 70649 |1960= 93460 |1970= 112230 |1980= 173036 |1990= 205775 |2000= 300904 |2010= 392365 |2020= 494967 |estyear=2025 |estimate=546141 |estref=<ref name="USCensusEst2025">{{cite web|url=https://www.census.gov/data/tables/time-series/demo/popest/2020s-counties-total.html|title=County Population Totals and Components of Change: 2020-2025|publisher=United States Census Bureau|access-date=April 15, 2026}}</ref> {{increase}} |align-fn=center |footnote=U.S. Decennial Census<ref>{{cite web|url=https://www.census.gov/programs-surveys/decennial-census.html|title=U.S. Decennial Census|publisher=United States Census Bureau |access-date=June 28, 2014}}</ref> 1790–1960<ref>{{cite web|url=http://mapserver.lib.virginia.edu|title=Historical Census Browser|publisher=University of Virginia Library|access-date=June 28, 2014}}</ref> 1900–1990<ref>{{cite web|url=https://www.census.gov/population/cencounts/id190090.txt|title=Population of Counties by Decennial Census: 1900 to 1990|publisher=United States Census Bureau|access-date=June 28, 2014}}</ref> 1990–2000<ref>{{cite web|url=https://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-url=https://web.archive.org/web/20100327165705/http://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-date=March 27, 2010 |url-status=live|title=Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000|publisher=United States Census Bureau|access-date=June 28, 2014}}</ref> 2010–2020<ref name="QF"/> | align = right }}

===2020 census===

As of the 2020 census, the county had a population of 494,967. The median age was 37.4 years. 23.5% of residents were under the age of 18 and 15.5% of residents were 65 years of age or older. For every 100 females there were 99.3 males, and for every 100 females age 18 and over there were 97.6 males age 18 and over.<ref name="Census2020DP">{{cite web|title=2020 Decennial Census Demographic Profile (DP1)|url=https://api.census.gov/data/2020/dec/dp?get=NAME,DP1_0021P,DP1_0024P,DP1_0025C,DP1_0049C,DP1_0045C,DP1_0069C,DP1_0073C,DP1_0125P,DP1_0126P,DP1_0129P,DP1_0138P,DP1_0139P,DP1_0141P,DP1_0142P,DP1_0143P,DP1_0145P,DP1_0146P,DP1_0147C,DP1_0148C,DP1_0149C,DP1_0156C,DP1_0157C,DP1_0158C,DP1_0159P,DP1_0160P&for=county%3A001&in=state%3A16|website=United States Census Bureau|year=2021|access-date=December 20, 2025|df=mdy}}</ref>

{| class="wikitable" style="text-align:center;" |+'''Ada County, Idaho – Racial and ethnic composition''' {{nobold|''Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.''}} !Race / Ethnicity (''NH = Non-Hispanic'') !Pop 2000<ref name=2000CensusP004>{{Cite web|title=P004: Hispanic or Latino, and Not Hispanic or Latino by Race – 2000: DEC Summary File 1 – Ada County, Idaho|url=https://data.census.gov/table/DECENNIALSF12000.P004?q=P004:+HISPANIC+OR+LATINO,+AND+NOT+HISPANIC+OR+LATINO+BY+RACE+[73]&g=050XX00US16001|publisher=United States Census Bureau |access-date=February 9, 2026|df=mdy }}</ref> !Pop 2010<ref name=2010CensusP2>{{Cite web|title=P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2010: DEC Redistricting Data (PL 94-171) - Ada County, Idaho|url=https://data.census.gov/table/DECENNIALPL2010.P2?q=p2&g=050XX00US16001|website=United States Census Bureau |access-date=February 9, 2026|df=mdy }}</ref> !{{partial|Pop 2020}}<ref name=2020CensusP2>{{Cite web|title=P2 Hispanic or Latino, and Not Hispanic or Latino by Race – 2020: DEC Redistricting Data (PL 94-171) - Ada County, Idaho|url=https://data.census.gov/table/DECENNIALPL2020.P2?q=p2&g=050XX00US16001|website=United States Census Bureau |access-date=February 9, 2026|df=mdy }}</ref> !% 2000 !% 2010 !{{partial|% 2020}} |- |White alone (NH) |272,569 |339,332 |style='background: #ffffe6; |397,998 |90.58% |86.48% |style='background: #ffffe6; |80.41% |- |Black or African American alone (NH) |1,829 |4,180 |style='background: #ffffe6; |7,733 |0.61% |1.07% |style='background: #ffffe6; |1.56% |- |Native American or Alaska Native alone (NH) |1,856 |2,058 |style='background: #ffffe6; |2,269 |0.62% |0.52% |style='background: #ffffe6; |0.46% |- |Asian alone (NH) |5,140 |9,234 |style='background: #ffffe6; |13,651 |1.71% |2.35% |style='background: #ffffe6; |2.76% |- |Pacific Islander alone (NH) |418 |817 |style='background: #ffffe6; |1,219 |0.14% |0.21% |style='background: #ffffe6; |0.25% |- |Other race alone (NH) |333 |505 |style='background: #ffffe6; |2,485 |0.11% |0.13% |style='background: #ffffe6; |0.50% |- |Mixed race or Multiracial (NH) |5,292 |8,334 |style='background: #ffffe6; |24,389 |1.76% |2.12% |style='background: #ffffe6; |4.93% |- |Hispanic or Latino (any race) |13,467 |27,905 |style='background: #ffffe6; |45,223 |4.48% |7.11% |style='background: #ffffe6; |9.14% |- |'''Total''' |'''300,904''' |'''392,365''' |style='background: #ffffe6; |'''494,967''' |'''100.00%''' |'''100.00%''' |style='background: #ffffe6; |'''100.00%''' |}

The racial makeup of the county was 82.9% White, 1.6% Black or African American, 0.7% American Indian and Alaska Native, 2.8% Asian, 0.3% Native Hawaiian and Pacific Islander, 3.3% from some other race, and 8.5% from two or more races. Hispanic or Latino residents of any race comprised 9.1% of the population.<ref name="Census2020PL">{{cite web|title=2020 Decennial Census Redistricting Data (Public Law 94-171)|url=https://api.census.gov/data/2020/dec/pl?get=NAME,P1_001N,P1_003N,P1_004N,P1_005N,P1_006N,P1_007N,P1_008N,P1_009N,P2_001N,P2_002N,H1_001N,H1_002N&for=county%3A001&in=state%3A16|website=United States Census Bureau|year=2021|access-date=December 20, 2025|df=mdy}}</ref>

94.4% of residents lived in urban areas, while 5.6% lived in rural areas.<ref name="Census2020DHC">{{cite web|title=2020 Decennial Census Demographic and Housing Characteristics (DHC)|url=https://api.census.gov/data/2020/dec/dhc?get=NAME,P2_002N,P2_003N&for=county%3A001&in=state%3A16|website=United States Census Bureau|year=2023|access-date=December 20, 2025|df=mdy}}</ref>

There were 187,488 households in the county, of which 31.7% had children under the age of 18 living with them and 23.4% had a female householder with no spouse or partner present. About 24.3% of all households were made up of individuals and 9.4% had someone living alone who was 65 years of age or older.<ref name="Census2020DP"/>

There were 196,901 housing units, of which 4.8% were vacant. Among occupied housing units, 69.1% were owner-occupied and 30.9% were renter-occupied. The homeowner vacancy rate was 1.1% and the rental vacancy rate was 5.8%.<ref name="Census2020DP"/>

===2010 census=== As of the 2010 census, there were 392,365 people, 148,445 households, and 99,282 families in the county. The population density was {{convert|372.8|PD/sqmi}}. There were 159,471 housing units at an average density of {{convert|151.5|/sqmi}}. The racial makeup of the county was 90.3% white, 2.4% Asian, 1.1% black or African American, 0.7% American Indian, 0.2% Pacific islander, 2.4% from other races, and 2.8% from two or more races. Those of Hispanic or Latino origin made up 7.1% of the population. In terms of ancestry, 19.4% were German, 15.9% were English, 11.8% were Irish, and 8.6% were American.

Of the 148,445 households, 35.6% had children under the age of 18 living with them, 52.4% were married couples living together, 10.0% had a female householder with no husband present, 33.1% were non-families, and 25.0% of all households were made up of individuals. The average household size was 2.58 and the average family size was 3.11. The median age was 34.8 years.

The median income for a household in the county was $55,835 and the median income for a family was $67,519. Males had a median income of $48,290 versus $34,875 for females. The per capita income for the county was $27,915. About 6.9% of families and 10.2% of the population were below the poverty line, including 11.8% of those under age 18 and 6.8% of those age 65 or over.

===2000 census=== As of the 2000 census, there were 300,904 people, 113,408 households, and 77,344 families in the county. The population density was {{convert|285|/mi2|/km2|abbr=on}}. There were 118,516 housing units at an average density of {{convert|112|/mi2|/km2|abbr=on}}. The racial makeup of the county was 92.86% White, 0.65% Black or African American, 0.69% Native American, 1.74% Asian, 0.15% Pacific Islander, 1.67% from other races, and 2.24% from two or more races. Hispanic or Latino residents of any race were 4.48% of the population.

There were 113,408 households, out of which 36.20% had children under the age of 18 living with them, 55.10% were married couples living together, 9.40% had a female householder with no husband present, and 31.80% were non-families. 23.80% of all households were made up of individuals, and 6.07% had someone living alone who was 65 years of age or older. The average household size was 2.59 and the average family size was 3.11.

The county population contained 27.30% under the age of 18, 10.30% from 18 to 24, 32.50% from 25 to 44, 20.80% from 45 to 64, and 9.10% who were 65 years of age or older. The median age was 33 years. For every 100 females, there were 100.6 males. For every 100 females age 18 and over, there were 98.9 males.

The median income for a household in the county was $46,140, and the median income for a family was $54,416. Males had a median income of $37,867 versus $26,453 for females. The per capita income for the county was $22,519. About 5.40% of families and 7.70% of the population were below the poverty line, including 9.20% of those under age 18 and 5.70% of those age 65 or over.

==Government and politics== Ada County has traditionally been rather conservative for an urban county. Like Idaho as a whole, it has long been a Republican Party stronghold. The last victory in a presidential election by a Democrat in Ada County was by Franklin D. Roosevelt in 1936. It rejected Lyndon B. Johnson in 1964 during his 44-state landslide. Barry Goldwater carried it by 13 points, a major reason why Idaho was Johnson's closest state.<ref>{{cite web|url=http://uselectionatlas.org/RESULTS/state.php?f=0&fips=16&year=1964|title=1964 Presidential General Election Results - Idaho|access-date=January 2, 2018}}</ref> In 2008 the presidential election in Ada County was more competitive than in previous years; John McCain defeated Barack Obama by six percentage points. Obama became the first Democrat to garner as much as 40 percent of the county's vote since Lyndon B. Johnson. In 2016, Donald Trump won the county by only a plurality due to high third party performance. In 2020, whereas the state of Idaho voted very strongly for Trump, he carried Ada County by a slim majority, only beating Joe Biden by around 3 percentage points. The election was close due to Biden's strength in Boise's downtown urban core, which gave him 59.2% of the vote to Trump's 37.4%.<ref>{{Cite web |title=ID 2022 Congressional |url=https://davesredistricting.org/maps#viewmap::ebc8cec8-b919-4a66-9b42-9cf5bf7e02a1 |access-date=August 24, 2023 |website=Dave's Redistricting}}</ref> This is the narrowest election in decades for Ada County, and the closest a Democrat has come to carrying the county since 1940.<ref>[http://www.sos.idaho.gov/ELECT/results/2008/General/county1.htm 2008 - General Election Ada County] {{webarchive |url=https://web.archive.org/web/20150321125940/http://www.sos.idaho.gov/ELECT/results/2008/General/county1.htm|date=March 21, 2015}}</ref> Yet, in 2024, this trend reversed, with Trump once again taking the majority in the county with 53.76% of the vote. This was the best performance for a Republican presidential candidate in Ada County since Mitt Romney in 2012.

Democratic gubernatorial nominee Jerry Brady carried the county in his 2002 and 2006 races, despite losing statewide in both contests.<ref>[http://www.idsos.state.id.us/elect/RESULTS/2006/general/cnty_governor.htm November 5, 2002 General Election Results] {{webarchive|url=https://web.archive.org/web/20080827184511/http://www.idsos.state.id.us/elect/RESULTS/2006/general/cnty_governor.htm|date=August 27, 2008}}</ref><ref>[http://www.idsos.state.id.us/elect/RESULTS/2006/general/cnty_governor.htm November 7, 2006 General Election Results] {{webarchive|url=https://web.archive.org/web/20080827184511/http://www.idsos.state.id.us/elect/RESULTS/2006/general/cnty_governor.htm|date=August 27, 2008 }}</ref> Another prominent Democrat, Boise mayor David Bieter, was elected in 2007, 2011 and 2015.<ref>[http://www.montanasnewsstation.com/global/story.asp?s=7324343 Bieter beats Tibbs in Boise mayor race] {{webarchive|url=https://web.archive.org/web/20110714113007/http://www.montanasnewsstation.com/global/story.asp?s=7324343|date=July 14, 2011}}</ref><ref>{{cite web|url=http://www.kivitv.com/news/political/elections/live-ada-canyon-boise-county-elections-2015|title=LIVE Elections Results 2015: Boise City, Ada and Canyon County - Story|access-date=January 7, 2016|url-status=dead|archive-url=https://web.archive.org/web/20160304195726/http://www.kivitv.com/news/political/elections/live-ada-canyon-boise-county-elections-2015|archive-date=March 4, 2016}}</ref>

Ada County is split between the first and second congressional districts; it is the only county in the state that is not located entirely within one district. As of 2022, the first district is represented by Russ Fulcher and includes Meridian, Eagle and Kuna, while the second district is represented by Mike Simpson and includes most of Boise proper. Both Fulcher and Simpson are Republicans.

In the Idaho Legislature, Ada County is split among nine districts, the most of any county.<ref>[http://www.legislature.idaho.gov/about/07districtmap.pdf Idaho Legislative District Map] {{webarchive|url=https://web.archive.org/web/20111117123303/http://legislature.idaho.gov/about/07districtmap.pdf |archive-url=https://web.archive.org/web/20070221170153/http://www.legislature.idaho.gov/about/07districtmap.pdf |archive-date=February 21, 2007 |url-status=live|date=November 17, 2011}}</ref> Each district elects one state senator and two state representatives. As of 2022, In the state senate, Republicans hold five seats and Democrats hold four. In the state house, Republicans hold ten seats and Democrats hold eight. Generally, Democratic strength is concentrated in Boise itself, while Republican strength is concentrated in the western suburbs.<ref>{{cite web|url=http://www.legislature.idaho.gov/about/district.cfm|title=Idaho Legislative Districts|access-date=January 2, 2018|url-status=dead|archive-url=https://web.archive.org/web/20081110195208/http://www.legislature.idaho.gov/about/district.cfm|archive-date=November 10, 2008}}</ref> Several of the Boise seats were Democratic pickups in 2006.<ref>{{cite web|url=http://www.ridenbaugh.com/index.php/2007/12/27/baseline-08-idaho-legislature/|title=Baseline 08: Idaho Legislature|website=Ridenbaugh Press|access-date=January 2, 2018}}</ref>

Each party held all of their respective legislative seats in the 2008 elections, but Republicans won two competitive county commission races.<ref>{{cite web|url=http://www.idahostatesman.com/election/story/563294.html|title=Election shows GOP still has the edge in Ada County|access-date=January 2, 2018}}</ref>

{| class="wikitable" |+Ada County registered voters by political party (as of November 2, 2020)<ref>{{Cite web|url=https://sos.idaho.gov/elect/VoterReg/2020/04/partybycounty.html|title=Voter Registration Totals as of April 6, 2020|website=sos.idaho.gov|access-date=June 5, 2020}}</ref> |Political Party |'''Constitution''' |'''Democratic''' |'''Libertarian''' |'''Republican''' |'''Unaffiliated''' |'''Total registered voters''' |- |Number of registered voters |921 |60,167 |4,199 |161,707 |100,962 |327,956 |} {{PresHead|place=Ada County, Idaho|source=<ref>{{cite web|url=http://uselectionatlas.org/RESULTS|title=Atlas of US Presidential Elections|first=David|last=Leip|website=uselectionatlas.org|access-date=November 16, 2025}}</ref>}}  {{PresRow|1892|Populist|1,170|0|1,657|Idaho}} {{PresRow|1896|Democratic|851|1,531|27|Idaho}} {{PresRow|1900|Republican|2,706|2,072|0|Idaho}} {{PresRow|1904|Republican|4,536|1,466|524|Idaho}} {{PresRow|1908|Republican|4,778|3,721|503|Idaho}} {{PresRow|1912|Progressive|3,198|2,569|4,227|Idaho}} {{PresRow|1916|Republican|5,299|5,207|460|Idaho}} {{PresRow|1920|Republican|8,419|4,173|27|Idaho}} {{PresRow|1924|Republican|7,220|3,780|2,255|Idaho}} {{PresRow|1928|Republican|10,279|3,921|108|Idaho}} {{PresRow|1932|Democratic|8,055|8,836|631|Idaho}} {{PresRow|1936|Democratic|7,581|12,027|966|Idaho}} {{PresRow|1940|Republican|12,861|12,381|51|Idaho}} {{PresRow|1944|Republican|13,410|10,667|67|Idaho}} {{PresRow|1948|Republican|14,972|11,253|480|Idaho}} {{PresRow|1952|Republican|27,415|10,281|40|Idaho}} {{PresRow|1956|Republican|26,387|11,328|0|Idaho}} {{PresRow|1960|Republican|27,703|17,017|0|Idaho}} {{PresRow|1964|Republican|25,404|19,639|0|Idaho}} {{PresRow|1968|Republican|30,185|11,529|6,167|Idaho}} {{PresRow|1972|Republican|36,665|12,687|4,959|Idaho}} {{PresRow|1976|Republican|41,135|21,125|1,629|Idaho}} {{PresRow|1980|Republican|55,205|21,324|10,015|Idaho}} {{PresRow|1984|Republican|60,036|21,760|1,128|Idaho}} {{PresRow|1988|Republican|54,951|30,525|1,858|Idaho}} {{PresRow|1992|Republican|49,000|31,941|29,225|Idaho}} {{PresRow|1996|Republican|61,811|43,040|12,892|Idaho}} {{PresRow|2000|Republican|75,050|40,650|7,785|Idaho}} {{PresRow|2004|Republican|94,641|58,523|1,866|Idaho}} {{PresRow|2008|Republican|93,328|82,236|5,196|Idaho}} {{PresRow|2012|Republican|97,554|77,137|7,555|Idaho}} {{PresRow|2016|Republican|93,752|75,677|26,240|Idaho}} {{PresRow|2020|Republican|130,699|120,539|10,250|Idaho}} {{PresRow|2024|Republican|143,759|116,116|9,558|Idaho}} {{PresFoot}}

===County offices=== The county government is administered by the Ada County Board of Commissioners, a three-member legislative body. Other elected officials include clerk, treasurer, sheriff, assessor, coroner, and prosecutor.<ref>{{cite web|url=http://www.adaweb.net/|title=Ada County|website=Adaweb.net|access-date=January 2, 2018}}</ref>

{| class="wikitable" style= margin:10px" |+County elected offices |- ! colspan="2" style="text-align:center; vertical-align:bottom;"| Office ! style="text-align:center;" | Office holder ! valign=bottom | Party |- | style="background-color:{{party color|Republican Party (United States)}}" | | Assessor<ref>{{cite web|url=https://adacounty.id.gov/Assessor|title=Assessor|website=Adacounty.id.gov|access-date=January 2, 2018}}</ref> | Rebecca Arnold | style="text-align:center;" | Republican |- | style="background-color:{{party color|Republican Party (United States)}}" | | Clerk of the Circuit Court<ref>{{cite web|url=https://adacounty.id.gov/clerk|title=Ada County Clerk Auditor Recorder > Home|website=Adacounty.id.gov|access-date=March 14, 2019}}</ref> | Trent Tripple | style="text-align:center;" | Republican |- | style="background-color:{{party color|Republican Party (United States)}}" | | County Commissioner District 1<ref>{{cite web|url=https://adacounty.id.gov/commissioners/ryan-davidson-district-1/|title=Ryan Davidson, Dist. 1|website=Adacounty.id.gov|access-date=March 22, 2021}}</ref> | Ryan Davidson | style="text-align:center;" | Republican |- | style="background-color:{{party color|Republican Party (United States)}}" | | County Commissioner District 2<ref>{{cite web|url=https://adacounty.id.gov/Commissioners/Commissioner-Bios/Rick-Visser-Dist-2|title=Rick Visser, Dist. 2|website=Adacounty.id.gov|access-date=January 2, 2018}}</ref> | Rod Beck (chair of the board) | style="text-align:center;" | Republican |- | style="background-color:{{party color|Republican Party (United States)}}" | | County Commissioner District 3<ref>{{cite web|url=https://adacounty.id.gov/commissioners/kendra-kenyon-dist-3/|title=Kendra Kenyon, Dist. 3|website=Adacounty.id.gov|access-date=March 14, 2019}}</ref> |Tom Dayley | style="text-align:center;" | Republican |- | style="background-color:{{party color|Republican Party (United States)}}" | | Coroner<ref>{{cite web|url=https://adacounty.id.gov/coroner|title=Coroner|website=Adacounty.id.gov|access-date=January 2, 2018}}</ref> | Richard Riffle | style="text-align:center;" | Republican |- | style="background-color:{{party color|Republican Party (United States)}}" | | Prosecutor<ref>{{cite web|url=https://adacounty.id.gov/prosecutor|title=Ada County Prosecutor|website=Adacounty.id.gov|access-date=January 2, 2018}}</ref> | Jan M. Bennetts | style="text-align:center;" | Republican |- | style="background-color:{{party color|Republican Party (United States)}}" | | Sheriff<ref>{{cite web|url=https://adasheriff.org|title=Ada County Sheriff > Home|website=Adasheriff.org|access-date=January 2, 2018}}</ref> | Matthew Clifford | style="text-align:center;" | Republican |- | style="background-color:{{party color|Republican Party (United States)}}" | | Treasurer<ref>{{cite web|url=https://adacounty.id.gov/treasurer|title=Treasurer|website=Adacounty.id.gov|access-date=March 14, 2019}}</ref> | Elizabeth Mahn | style="text-align:center;" | Republican |}

The Idaho Department of Correction operates the South Boise Prison Complex,<ref>[http://www.idoc.idaho.gov/sites/default/files/webfm/documents/business_services/management_services/IT%20Projects.pdf Information Technology Projects]. Idaho Department of Correction. March 2011. Retrieved on June 3, 2011.</ref> a correctional facility located in unincorporated Ada County, south of the Boise Airport and east of Kuna.<ref>[http://www.idoc.idaho.gov/content/locations Locations]. Idaho Department of Correction. Retrieved on June 4, 2011.</ref>

==Education== ;Public School districts School districts include:<ref>{{cite map|author=Geography Division|url=https://www2.census.gov/geo/maps/DC2020/PL20/st16_id/schooldistrict_maps/c16001_ada/DC20SD_C16001.pdf |archive-url=https://web.archive.org/web/20220721202215/https://www2.census.gov/geo/maps/DC2020/PL20/st16_id/schooldistrict_maps/c16001_ada/DC20SD_C16001.pdf |archive-date=July 21, 2022 |url-status=live|title=2020 CENSUS - School District Reference Map: Ada County, ID|publisher=United States Census Bureau|place=Suitland, Maryland|date=December 23, 2020|accessdate=July 21, 2022}} - [https://www2.census.gov/geo/maps/DC2020/PL20/st16_id/schooldistrict_maps/c16001_ada/DC20SD_C16001_SD2MS.txt Text list]</ref> {{Div col}} * Boise School District * Kuna Joint School District 3 * Melba Joint School District 136 * West Ada School District (Meridian Joint School District 2) {{div col end}}

Residents are in the area (and the taxation zone) for College of Western Idaho.<ref>{{cite web|url=https://legislature.idaho.gov/wp-content/uploads/budget/committee/jfac/2022/C3.Wednesday,%20January%2026/03.College%20of%20Western%20Idaho.pdf|title=College of Western Idaho, pg. 1-77|publisher=Idaho Legislature|date=January 26, 2022|access-date=March 12, 2024}} - See the map. Also see area 3 in: {{cite web|url=https://legislature.idaho.gov/statutesrules/idstat/Title33/T33CH21/SECT33-2101/|title=TITLE 33 EDUCATION CHAPTER 21 JUNIOR COLLEGES|publisher=Idaho Legislature|access-date=March 12, 2024}}</ref>

==Communities== ===Cities=== {{div col}} * Boise (county seat and state capital) * Eagle * Garden City * Kuna * Meridian * Star {{div col end}}

===Census-designated places=== * Avimor<ref name="CenPopGazetteer2020">{{cite web|title=2020 U.S. Gazetteer Files|url=https://www2.census.gov/geo/docs/maps-data/data/gazetteer/2020_Gazetteer/2020_gaz_place_16.txt|publisher=United States Census Bureau|accessdate=April 8, 2020}}</ref> * Hidden Springs

===Unincorporated communities=== {{div col}} * Mora<ref>[https://www.google.com/maps/place/Mora,+ID+83634/@43.4596243,-116.3619505,15z/data=!3m1!4b1!4m13!1m7!3m6!1s0x54aef4cf3ac62cc9:0xc30a558e3dd87d03!2sAda+County,+ID!3b1!8m2!3d43.478767!4d-116.2420304!3m4!1s0x54ae44ae75aebbcf:0xb118287253eee84b!8m2!3d43.4596478!4d-116.3531113 ''Mora ID'' Google Maps (accessed January 16, 2019)]</ref> * Pleasant Valley<ref>[https://www.google.com/maps/place/Pleasant+Valley,+ID+83634/@43.444626,-116.2558349,15z/data=!3m1!4b1!4m13!1m7!3m6!1s0x54aef4cf3ac62cc9:0xc30a558e3dd87d03!2sAda+County,+ID!3b1!8m2!3d43.478767!4d-116.2420304!3m4!1s0x54ae5c4eb16ad375:0x4e46e4588ff51a37!8m2!3d43.4446937!4d-116.2470245 ''Pleasant Valley ID'' Google Maps (accessed January 16, 2019)]</ref> * Sonna<ref>[https://www.google.com/maps/place/Sonna,+ID+83642/@43.6096224,-116.4655693,15z/data=!3m1!4b1!4m13!1m7!3m6!1s0x54aef4cf3ac62cc9:0xc30a558e3dd87d03!2sAda+County,+ID!3b1!8m2!3d43.478767!4d-116.2420304!3m4!1s0x54ae525cae88ae29:0x2698147a0b8a60fb!8m2!3d43.609731!4d-116.4567947 ''Sonna ID'' Google Maps (accessed January 16, 2019)]</ref> {{div col end}}

===Population ranking=== The population ranking of the following table is based on the 2020 census of Ada County.

'''†''' ''county seat''

{| class="wikitable sortable" |- ! Rank !! Cities !! Municipal type !! Population (2022 Estimate) !! Population (2020 Census) |- style=background-color:#FFFACD | 1 || '''†''' '''Boise''' || City || 236,634 || 235,684 |- style=background-color:#FFFACD | 2 || '''Meridian''' || City || 129,736 || 117,635 |- style=background-color:#FFFACD | 3 || '''Eagle''' || City || 32,399 || 30,346 |- style=background-color:#FFFACD | 4 || '''Kuna''' || City || 27,229 || 24,011 |- style=background-color:#FFFACD | 5 || '''Star''' || City || 14,646 || 11,117 |- style=background-color:#FFFACD | 6 || '''Garden City''' || City || 12,927 || 12,316 |- style=background-color:#F0FFF0 | 7 || '''Hidden Springs''' || CDP || — || 3,076 |- style=background-color:#F0FFF0 | 8 || '''Avimor''' || CDP || — || 1,255 |}

==References== {{Reflist|30em}}

==Further reading== * {{cite web|title=Ada County|work=State website|url=http://www.idaho.gov/aboutidaho/county/ada.html|access-date=September 20, 2005|url-status=dead|archive-url=https://web.archive.org/web/20051126071955/http://www.idaho.gov/aboutidaho/county/ada.html|archive-date=November 26, 2005}}

==External links== * {{official website|http://www.adaweb.net}}

{{Geographic Location |Centre = Ada County, Idaho |Northeast = Boise County |East = Elmore County |South = Owyhee County |West = Canyon County |Northwest = Gem County }} {{Ada County, Idaho}} {{Idaho county seats}} {{NRHP in Idaho by county}} {{Idaho}} {{authority control}} {{coord|43.45|-116.24|display=title|type:adm2nd_region:US-ID_source:UScensus1990}}

Category:Ada County, Idaho Category:Idaho counties Category:1864 establishments in Idaho Territory Category:Boise metropolitan area Category:Populated places in the United States established in 1864