Flathead County area

Population and density of Flathead County

The Census Bureau estimates that 115,429 people lived in Flathead County on July 1, 2025. That ranks #564 of 3,222 county equivalents nationally and #4 of 56 in Montana. Since the April 1, 2020 estimates base of 104,353, the population has grown by 11,076 (+10.6%), compared with +5.6% for Montana as a whole.

With 5,087.3 square miles of land, that is 23 people per square mile (8.8 per km²), placing Flathead County #2,217 nationally for density and #6 in Montana. The median county equivalent has 47 people per square mile; the Montana median is 2.8. Put another way, there are about 28 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 Flathead County

3 incorporated places lie at least partly in Flathead County. Together they are home to 46,962 people (40.7%); the other 68,467 (59.3%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Kalispell city, with 31,851 residents in the county. Among places with at least 1,000 residents in 2020, Kalispell city grew fastest since then (+27%).

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

Metropolitan area

Flathead County is a central county of the Kalispell, MT Micropolitan Statistical Area. Flathead County is the area’s only county equivalent, so the micro area has the same 5,087.3 square miles of land. By combined land it ranks #19 of 542 micropolitan areas, and #20 by population.

ZIP codes

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

59845599015991159912599135991659919599205992259925599265992759928599325993659937

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 Flathead County

Flathead County shares a land border with 9 county equivalents. It has more land than every one of them. The largest neighbor is Lincoln County (3,612.6 mi²) and the smallest is Lake County (1,490.5 mi²). Together with its neighbors, Flathead County forms a block of 28,219.5 mi² of land, of which it holds 18%.

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

Flathead County has more land than 3 of the 50 states. It is about 1.1 times the land area of Connecticut (4,842.5 mi²), while Hawaii, the next larger state, has 1.3 times as much land (6,422.6 mi²). Montana’s county land could hold about 29 areas the size of Flathead County.

Another way to picture it: the same land area would fill a square about 71.3 miles (114.8 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 Flathead County?

Flathead County has more land than 3,146 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 Flathead County at #78 nationally by total area, 2 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 3.2%, compared with a national county-equivalent median of 1.2% — 2 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 Flathead 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.