Bonneville County area

Population and density of Bonneville County

The Census Bureau estimates that 135,771 people lived in Bonneville County on July 1, 2025. That ranks #492 of 3,222 county equivalents nationally and #4 of 44 in Idaho. Since the April 1, 2020 estimates base of 123,959, the population has grown by 11,812 (+9.5%), compared with +10.4% for Idaho as a whole.

With 1,866 square miles of land, that is 73 people per square mile (28 per km²), placing Bonneville County #1,229 nationally for density and #6 in Idaho. The median county equivalent has 47 people per square mile; the Idaho median is 10. Put another way, there are about 8.8 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 Bonneville County

7 incorporated places lie at least partly in Bonneville County. Together they are home to 96,972 people (71.4%); the other 38,799 (28.6%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Idaho Falls city, with 71,785 residents in the county. Among places with at least 1,000 residents in 2020, Iona city grew fastest since then (+16.6%).

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

Metropolitan area

Bonneville County is a central county of the Idaho Falls, ID Metropolitan Statistical Area. Its 3 county equivalents have 173,851 residents on 5,196.1 square miles of land; Bonneville County accounts for 35.9% of the land and 78.1% of the residents. By combined land it ranks #48 of 393 metropolitan areas, and #260 by population. It belongs to the Idaho Falls-Rexburg-Blackfoot, ID Combined Statistical Area.

ZIP codes

14 ZIP Code Tabulation Areas have land in Bonneville County; 11 of them have most of their land inside the county, and the others mainly cover neighboring areas.

8312083274832858340183402834048340683427834288344283443834448344983454

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 Bonneville County

Bonneville County shares a land border with 7 county equivalents, including 2 in Wyoming. It has more land than 4 of them. The largest neighbor is Lincoln County (4,075.3 mi²) and the smallest is Teton County (449.1 mi²). Together with its neighbors, Bonneville County forms a block of 15,808.1 mi² of land, of which it holds 11.8%.

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

Bonneville County has more land than 1 of the 50 states. It is about 1.8 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 44 areas the size of Bonneville County.

Another way to picture it: the same land area would fill a square about 43.2 miles (69.5 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 Bonneville County?

Bonneville County has more land than 2,912 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 Bonneville County at #344 nationally by total area, 34 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 1.8%, compared with a national county-equivalent median of 1.2% — 0.6 percentage points higher. 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 Bonneville 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.