Fremont County area

Population and density of Fremont County

The Census Bureau estimates that 14,208 people lived in Fremont County on July 1, 2025. That ranks #2,216 of 3,222 county equivalents nationally and #23 of 44 in Idaho. Since the April 1, 2020 estimates base of 13,387, the population has grown by 821 (+6.1%), compared with +10.4% for Idaho as a whole.

With 1,864 square miles of land, that is 7.6 people per square mile (2.9 per km²), placing Fremont County #2,736 nationally for density and #27 in Idaho. The median county equivalent has 47 people per square mile; the Idaho median is 10. Put another way, there are about 84 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 Fremont County

8 incorporated places lie at least partly in Fremont County. Together they are home to 6,622 people (46.6%); the other 7,586 (53.4%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is St. Anthony city, with 3,990 residents in the county. By land, Island Park city is the largest at 6.082 mi².

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

Metropolitan area

Fremont County is an outlying county of the Rexburg, ID Micropolitan Statistical Area. Its 2 county equivalents have 69,380 residents on 2,333.2 square miles of land; Fremont County accounts for 79.9% of the land and 20.5% of the residents. By combined land it ranks #65 of 542 micropolitan areas, and #114 by population. It belongs to the Idaho Falls-Rexburg-Blackfoot, ID Combined Statistical Area.

ZIP codes

11 ZIP Code Tabulation Areas have land in Fremont County; 6 of them have most of their land inside the county, and the others mainly cover neighboring areas.

8342083421834258342983433834368343883440834458344883451

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 Fremont County

Fremont County shares a land border with 8 county equivalents, including 4 in Wyoming and Montana. It has more land than 4 of them. The largest neighbor is Beaverhead County (5,542.7 mi²) and the smallest is Teton County (449.1 mi²). Together with its neighbors, Fremont County forms a block of 21,372.2 mi² of land, of which it holds 8.7%.

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

Fremont 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 Fremont 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 Fremont County?

Fremont County has more land than 2,911 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 Fremont County at #345 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 1.7%, compared with a national county-equivalent median of 1.2% — 0.5 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 Fremont 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.