Twin Falls County area

Population and density of Twin Falls County

The Census Bureau estimates that 97,539 people lived in Twin Falls County on July 1, 2025. That ranks #646 of 3,222 county equivalents nationally and #5 of 44 in Idaho. Since the April 1, 2020 estimates base of 90,050, the population has grown by 7,489 (+8.3%), compared with +10.4% for Idaho as a whole.

With 1,921.7 square miles of land, that is 51 people per square mile (20 per km²), placing Twin Falls County #1,533 nationally for density and #8 in Idaho. The median county equivalent has 47 people per square mile; the Idaho median is 10. Put another way, there are about 13 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 Twin Falls County

8 incorporated places lie at least partly in Twin Falls County. Together they are home to 71,569 people (73.4%); the other 25,970 (26.6%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Twin Falls city, with 56,216 residents in the county. Among places with at least 1,000 residents in 2020, Kimberly city grew fastest since then (+25.4%).

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

Metropolitan area

Twin Falls County is a central county of the Twin Falls, ID Metropolitan Statistical Area. Its 2 county equivalents have 123,901 residents on 2,519.3 square miles of land; Twin Falls County accounts for 76.3% of the land and 78.7% of the residents. By combined land it ranks #130 of 393 metropolitan areas, and #333 by population.

ZIP codes

10 ZIP Code Tabulation Areas have land in Twin Falls County; 8 of them have most of their land inside the county, and the others mainly cover neighboring areas.

83301833028331483316833218332883332833348334183344

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 Twin Falls County

Twin Falls County shares a land border with 6 county equivalents, including 1 in Nevada. It has more land than 2 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, Twin Falls County forms a block of 33,730.8 mi² of land, of which it holds 5.7%.

How big is Twin Falls County compared with U.S. states?

Twin Falls County has more land than 1 of the 50 states. It is about 1.9 times the land area of Rhode Island (1,033.9 mi²), while Delaware, the next larger state, has 1 times as much land (1,948.6 mi²). Idaho’s county land could hold about 43 areas the size of Twin Falls County.

Another way to picture it: the same land area would fill a square about 43.8 miles (70.5 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 Twin Falls County?

Twin Falls County has more land than 2,925 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 Twin Falls County at #332 nationally by total area, 35 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 0.4%, compared with a national county-equivalent median of 1.2% — 0.8 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 Twin Falls 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.