Cassia County, Idaho Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 15th-largest in Idaho
The population of Cassia County, Idaho is 25,165 as of the 2023 American Community Survey, making it the 15th-largest county in Idaho. The median household income is $67,042, the median home value is $257,300, and the median age is 33.1.
The population of Cassia County has grown 12.5% since 2010 (23,080 → 25,976), a +0.85% annualized rate.
25,165
Population
+0.85%
Annual growth
10
People / sq mi
$67,042
Median Income
$257,300
Median Home Value
Cassia County covers 2,566 sq mi of land at 9.8 people per square mile.
About Cassia County, ID
Cassia County skews on age — the median resident is 33.1, younger than the national median. With 25,165 residents, Cassia County is a county in Idaho. It ranks #15 among counties in Idaho by population.
The typical household here earns about $67,042, below the US median of $78,538. Poverty is relatively low for US counties at 6.8%, below the national 12.4%. Home values run above average at $257,300, with typical rent around $920.
Roughly 20.9% of adults have a bachelor’s, below the national 35.0%. About 7.7% of the workforce is home-based, below the national 14.0%, and the average commute runs about 18 minutes each way.
Cassia County Population History (2010-2024)
The county of Cassia County had a population of 23,080 in 2010 and 25,976 in 2024, a 12.5% growth over 14 years. The peak was 25,976 in 2024. Average annual growth rate: 0.85%.
25,976
Population (2024)
23,080
Population (2010)
25,976
Peak (2024)
0.85%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 23,080 |
| 2011 | 23,111 |
| 2012 | 23,265 |
| 2013 | 23,344 |
| 2014 | 23,503 |
| 2015 | 23,497 |
| 2016 | 23,477 |
| 2017 | 23,661 |
| 2018 | 23,769 |
| 2019 | 24,052 |
| 2020 | 24,755 |
| 2021 | 25,242 |
| 2022 | 25,625 |
| 2023 | 25,817 |
| 2024 | 25,976 |
Race & Ethnicity
| White | 72.3% |
| Black or African American | 0.1% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 3.5% |
| Two or More Races | 0.0% |
Age & Sex
33.1
Median Age
48.6%
Female
51.4%
Male
13.7%
Age 65+
Age Distribution
Children (under 15): 25.5% · Seniors (65+): 13.7%
Income & Poverty
| Median household income | $67,042$-7,594 vs state |
| Mean household income | $88,788 |
| Per-capita income | $30,688 |
| Poverty rate | 6.8%-0.2% vs state |
| Unemployment rate | 1.7% |
| Employment-to-population | 64.4% |
Top Industries by Employment
The largest employment sector in Cassia County is professional & business services, accounting for 17.6% of workers.
How residents commute
0.2%
Drive alone
1.3%
Carpool
81.3%
Public transit
7.7%
Work from home
17.8 min
Avg commute
Housing
$257,300$-118,700 vs state
Median home value
$920
Median rent
70.0%
Homeownership rate
8,992
Total housing units
91.6%
Occupied
8.4%
Vacant
30.0%
Renter-occupied
Social & access
88.5%
With health insurance
93.3%
With broadband internet
30.9%
Foreign-born
4.4%
Veterans (18+)
13.5%
With a disability
78.9%
Speak language other than English at home
Education
85.4%
High School+
20.9%
Bachelor's+
Largest cities in Idaho
Other counties in Idaho
Part of Idaho
Metro areas in Idaho
County rankings
Frequently Asked Questions
Cassia County, Idaho has a population of 25,165 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 15th-largest county in Idaho. Population density is 10 people per square mile.
The population of Cassia County has grown 12.5% since 2010 (23,080 → 25,976), a +0.85% annualized rate.
The median household income in Cassia County, Idaho is $67,042, with mean (average) household income of $88,788 and per-capita income of $30,688. 6.8% of residents live below the federal poverty level.
In Cassia County, the largest racial and ethnic groups are White (72.3%), Hispanic or Latino (3.5%), Black or African American (0.1%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Cassia County, Idaho is 33.1 years. Residents are 48.6% female and 51.4% male.
The median home value in Cassia County is $257,300 and median monthly rent is $920. 70.0% of occupied housing units are owner-occupied. The county has 8,992 total housing units, 8.4% of which are vacant.
The largest employment sector in Cassia County, Idaho is professional, scientific, and management services, employing 17.6% of workers. The unemployment rate is 1.7%.
Boise City is among the largest cities associated with Cassia County, Idaho, with a population of 235,701.
Cassia County, ID Climate
Cassia County, ID has an average annual temperature of 4.8°C (41°F) and receives about 428 mm of precipitation per year. The warmest month is August and the coldest is January. Figures are 1970–2000 climate normals.
4.8°C
Avg Temp
428
Precip (mm/yr)
Aug
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -5° / 23° | 39 mm |
| February | -4° / 25° | 32 mm |
| March | -1° / 29° | 37 mm |
| April | 2° / 36° | 35 mm |
| May | 7° / 44° | 49 mm |
| June | 11° / 52° | 43 mm |
| July | 16° / 61° | 30 mm |
| August | 17° / 62° | 29 mm |
| September | 12° / 54° | 28 mm |
| October | 7° / 44° | 30 mm |
| November | 0° / 32° | 37 mm |
| December | -4° / 24° | 39 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Cassia County, ID
The most comfortable months to visit Cassia County, ID are typically August, July and September, when temperatures are mildest and rainfall is relatively low. The hottest month is August (around 25°C high). The coldest is January (near -10°C low). May is usually the wettest month.
Where to stay near Cassia County
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Population, race, income, age, and trends across Idaho
Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.