Cassia County area

Population and density of Cassia County

The Census Bureau estimates that 26,397 people lived in Cassia County on July 1, 2025. That ranks #1,608 of 3,222 county equivalents nationally and #15 of 44 in Idaho. Since the April 1, 2020 estimates base of 24,688, the population has grown by 1,709 (+6.9%), compared with +10.4% for Idaho as a whole.

With 2,565.6 square miles of land, that is 10 people per square mile (4 per km²), placing Cassia County #2,636 nationally for density and #22 in Idaho. The median county equivalent has 47 people per square mile; the Idaho median is 10. Put another way, there are about 62 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Cassia County

5 incorporated places lie at least partly in Cassia County. Together they are home to 13,708 people (51.9%); the other 12,689 (48.1%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Burley city, with 12,053 residents in the county (the city extends into 1 other county).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Cassia County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Cassia County is a central county of the Burley, ID Micropolitan Statistical Area. Its 2 county equivalents have 49,308 residents on 3,322.8 square miles of land; Cassia County accounts for 77.2% of the land and 53.5% of the residents. By combined land it ranks #42 of 542 micropolitan areas, and #230 by population.

ZIP codes

9 ZIP Code Tabulation Areas have land in Cassia County; 7 of them have most of their land inside the county, and the others mainly cover neighboring areas.

832118331183312833188332383342833448334683350

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Cassia County

Cassia County shares a land border with 8 county equivalents, including 2 in Utah and Nevada. It has more land than 5 of them. The largest neighbor is Elko County (17,173.3 mi²) and the smallest is Jerome County (597.5 mi²). Together with its neighbors, Cassia County forms a block of 34,037.2 mi² of land, of which it holds 7.5%.

How big is Cassia County compared with U.S. states?

Cassia County has more land than 2 of the 50 states. It is about 1.3 times the land area of Delaware (1,948.6 mi²), while Connecticut, the next larger state, has 1.9 times as much land (4,842.5 mi²). Idaho’s county land could hold about 32 areas the size of Cassia County.

Another way to picture it: the same land area would fill a square about 50.7 miles (81.5 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Cassia County?

Cassia County has more land than 3,012 of the other 3,221 county equivalents in the dataset.

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Cassia County at #224 nationally by total area, 14 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 0.6%, compared with a national county-equivalent median of 1.2% — 0.6 percentage points lower. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Cassia County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.