Overview
Ada County is home to 508,052 residents (Census ACS 5-Year, 2023), making it the most populous county in Idaho by a wide margin. It contains Boise, the state capital, and sits in the southwestern part of the state along the Boise River. With a population larger than 96% of all U.S. counties, Ada County functions as Idaho's economic and political center of gravity.
The county's median household income of $88,907 (Census ACS 5-Year, 2023) ranks higher than 92% of U.S. counties and places it near the top within Idaho, above 95% of the state's counties. Home values reflect that income: the median sits at $476,000 (Census ACS 5-Year, 2023), higher than 96% of counties nationally. Ada County is, by most economic measures, well above both state and national medians.
A labor force of 302,570 (BLS LAUS, 2025) and an unemployment rate of 3.1% (BLS LAUS, 2025) point to a tight job market. The county's 4.1% housing vacancy rate (Census ACS 5-Year, 2023) is lower than 98% of U.S. counties, which tells its own story about demand for housing here.
Demographics
Ada County skews young for a county of its size. The median age is 38.3 years (Census ACS 5-Year, 2023), lower than roughly 78% of U.S. counties. That's consistent with a metro area that has attracted working-age residents in recent years.
Educational attainment is a standout. Some 43.9% of residents hold a bachelor's degree or higher (Census ACS 5-Year, 2023), a rate higher than 94% of U.S. counties and above 91% of Idaho counties. The combination of state government, a university presence, and a growing technology sector likely contributes to that concentration of college graduates.
The racial composition is predominantly white at 81.6% (Census ACS 5-Year, 2023), which places Ada County near the middle of U.S. counties on that measure (51st nationally). Hispanic residents make up 9.5%, Asian residents 2.5%, Black residents 1.2%, and Native American residents 0.3% (all Census ACS 5-Year, 2023). The Asian population share is higher than 87% of U.S. counties, notable for a county in the Mountain West.
Education
Per-pupil spending in Ada County is $9,635 (Education Data Portal, 2020), well below the national average of roughly $15,000. That figure ranks lower than 99% of U.S. counties, placing Ada County near the very bottom nationally on school funding. Within Idaho, it falls at about the 36th range among counties.
Total enrollment stands at 80,166 students (Education Data Portal, 2021), larger than 96% of U.S. counties. The student-teacher ratio is 17.4:1 (Education Data Portal, 2021), above the national average of about 15.5:1 and higher than 89% of counties. Larger class sizes paired with low per-pupil spending suggest schools here are stretched thin relative to the county's overall wealth.
The graduation rate is 75.2% (Education Data Portal, 2019), below the national average of roughly 87% and lower than about 92% of U.S. counties. Within Idaho, Ada County's graduation rate sits below 81% of counties. For a county with such high educational attainment among adults, the gap between K-12 outcomes and adult degree-holding rates is striking. It suggests that much of the county's college-educated population arrived from elsewhere rather than being produced by local schools.
Economy & Employment
The unemployment rate of 3.1% (BLS LAUS, 2025) is lower than roughly 75% of U.S. counties, reflecting a labor market where most people who want work can find it. Out of a labor force of 302,570, just 9,390 were unemployed (BLS LAUS, 2025). Employment totaled 293,180 (BLS LAUS, 2025).
Median household income of $88,907 (Census ACS 5-Year, 2023) and per capita income of $47,768 (Census ACS 5-Year, 2023) both rank in the top 10% nationally. IRS data shows an average adjusted gross income of $106,498 per return (IRS Statistics of Income, 2021), with total AGI across 246,130 returns reaching $26.2 billion (IRS Statistics of Income, 2021). Average total income per return was $107,509 (IRS Statistics of Income, 2021).
The poverty rate is 8.3% (Census ACS 5-Year, 2023), lower than about 85% of U.S. counties. That's a relatively low poverty rate, but it still means roughly 42,000 residents live below the poverty line. In a county where the median home costs $476,000, even residents above the official poverty threshold can face real affordability pressure.
The mean commute time of 17.7 minutes (Census ACS 5-Year, 2023) is shorter than 85% of U.S. counties. Most residents aren't spending long in traffic, a practical quality-of-life factor that doesn't show up in income figures.
Housing & Cost of Living
The median home value of $476,000 (Census ACS 5-Year, 2023) puts Ada County in the top 4% nationally. Median gross rent is $1,465 per month (Census ACS 5-Year, 2023), higher than 93% of U.S. counties. These aren't San Francisco numbers, but they're high for the Mountain West and represent a significant jump from where Boise-area housing sat a decade ago.
HUD Fair Market Rents for 2026 give a detailed picture of rental costs. A studio apartment runs $1,170, a one-bedroom $1,381, a two-bedroom $1,655, a three-bedroom $2,318, and a four-bedroom $2,772 (HUD Fair Market Rents, 2026). The four-bedroom FMR is higher than 97% of U.S. counties, meaning families who need space face costs that rival much larger metro areas.
The vacancy rate of 4.1% (Census ACS 5-Year, 2023) is lower than 98% of U.S. counties. Out of 205,068 total housing units, just 8,368 sit vacant (Census ACS 5-Year, 2023). Supply is tight. When vacancy rates drop this low, renters have little bargaining power and prices tend to climb.
The ratio of home values to household income tells the affordability story in one number. At $476,000 to $88,907, a median-priced home costs about 5.4 times the median household income. Conventional lending guidelines consider anything above 3x to be a stretch. For first-time buyers without existing equity, the math is difficult.
Health & Wellness
Ada County's health outcomes are generally favorable compared to national figures, with some exceptions. The obesity rate is 28.9% (CDC PLACES, 2023), lower than 95% of U.S. counties. The diabetes rate of 8.0% (CDC PLACES, 2023) is lower than 97% of counties. High blood pressure affects 28.8% of adults (CDC PLACES, 2023), a rate lower than 88% of counties nationally.
Mental health is a different story. The depression rate is 25.5% (CDC PLACES, 2023), higher than 66% of U.S. counties. Some 15.8% of adults report frequent poor mental health days (CDC PLACES, 2023), a rate lower than 92% of counties, which is favorable but still means roughly one in six adults is affected.
Poor physical health days are reported by 11.8% of adults (CDC PLACES, 2023), lower than 86% of counties. Cholesterol screening stands at 81.8% (CDC PLACES, 2023). Annual checkup rates hit 75.1% (CDC PLACES, 2023), roughly in the middle of U.S. counties.
The uninsured rate of 8.7% (CDC PLACES, 2023) is lower than about 74% of U.S. counties. Within Idaho, Ada County has one of the lowest uninsured rates, below 98% of the state's counties. Idaho didn't expand Medicaid until 2020, and the effects of that expansion may still be filtering through these numbers.
Climate & Natural Disasters
Ada County gets just 14.1 inches of precipitation a year (NOAA Climate Data Online, 2025), lower than 96% of U.S. counties. That's genuinely dry. Snowfall averages 12.1 inches annually (NOAA, 2025), well below the national median.
Temperatures are moderate year-round. Average highs reach 66.9°F, lows sit around 44.3°F, and the mean annual temperature is 55.6°F (NOAA, 2025). All three measures are near the national midpoint. The semi-arid climate doesn't produce weather extremes that push counties into the record books.
The federal disaster history is short. FEMA has issued six declarations for the county across more than six decades, lower than 98% of U.S. counties for disaster frequency (FEMA OpenFEMA, 2026). Two of those were COVID-19 declarations in spring 2020. The others include a flood in 2017, a wildfire in 2000, and a flood in 1964. That's four climate-related events in 60-plus years. It's a low-risk profile by any measure.
The gap between low disaster counts and real physical risk is worth keeping in mind. Wildfire smoke is a regular summer presence, driven by fires across the broader region even when nothing's burning locally. Boise River flooding remains a periodic concern in lower-lying areas. Neither has produced frequent federal declarations, but both are getting worse as drought conditions deepen across the interior West. The dryness that keeps this county's disaster record clean is the same condition that makes fire weather more dangerous each decade.
Financial Profile
IRS data paints a picture of concentrated income. The 246,130 tax returns filed in Ada County generated $26.2 billion in total AGI and $26.5 billion in total income (IRS Statistics of Income, 2021). Average AGI per return was $106,498 and average total income was $107,509 (IRS Statistics of Income, 2021). Both figures rank above 94% of U.S. counties.
Banking access is modest for a county this size. Ada County has 7 FDIC-insured bank branches holding $1.28 billion in total deposits (FDIC Summary of Deposits, 2023). That branch count places the county around the 40th range nationally, which seems low for a county of 500,000. Credit unions and online banking likely fill the gap, but the FDIC data captures only traditional bank branches.
Social Security beneficiaries total 100,345 (SSA OASDI, 2024), or about 19.7% of the population. That's a lower share than in most counties, consistent with Ada County's younger median age. With 96% of counties having fewer OASDI beneficiaries in raw numbers, Ada County's Social Security population is substantial in absolute terms even if the per-capita rate is moderate.
Key Comparisons
Ada County consistently ranks in the top 5 to 10% of U.S. counties on economic measures. It sits above 92% of counties on household income, above 93% on per capita income, and above 96% on home values. Within Idaho, it leads on most income and employment metrics, ranking above 95% of the state's counties on household income and above 98% on labor force size.
The places where Ada County falls behind are notable. Per-pupil education spending (lower than 99% of counties nationally) and graduation rates (lower than 92%) stand in sharp contrast to the county's wealth. The adult population is highly educated, with bachelor's degree attainment above 94% of counties, but K-12 funding and outcomes don't match.
Housing costs rank in the top tier nationally. Fair market rents for three and four-bedroom units rank above 96% and 97% of counties, respectively. Paired with a vacancy rate lower than 98% of counties, the housing market favors sellers and landlords.
Health outcomes are mixed. Physical health indicators (obesity, diabetes, blood pressure) are better than the vast majority of counties. But depression rates rank higher than 66% of counties, a gap worth watching in a state that has historically had limited mental health infrastructure.
The county's 3.1% unemployment rate and 17.7-minute average commute suggest a labor market that functions well on the basics. Whether wages can keep pace with housing costs is the central tension in Ada County's economic profile.
Data Sources
- Census ACS 5-Year, 2023: Population, income, housing, demographics, education attainment, commute times, poverty rate
- BLS LAUS, 2025: Unemployment rate, labor force, employment counts
- CDC PLACES, 2023: Health metrics including obesity, diabetes, mental health, insurance coverage, preventive care
- HUD Fair Market Rents, 2026: Fair market rent by bedroom count
- FEMA OpenFEMA, 2026: Disaster declarations and history
- IRS Statistics of Income, 2021: Tax returns, adjusted gross income, total income
- FDIC Summary of Deposits, 2023: Bank branch counts and total deposits
- NOAA Climate Data Online, 2025: Temperature and precipitation averages
- SSA OASDI, 2024: Social Security beneficiary counts
- USDA Census of Agriculture, 2022: Data not available for Ada County
- Education Data Portal, 2021: Per-pupil spending, enrollment, student-teacher ratio, graduation rate