Gallatin County area

Population and density of Gallatin County

The Census Bureau estimates that 128,740 people lived in Gallatin County on July 1, 2025. That ranks #517 of 3,222 county equivalents nationally and #2 of 56 in Montana. Since the April 1, 2020 estimates base of 118,957, the population has grown by 9,783 (+8.2%), compared with +5.6% for Montana as a whole.

With 2,605.4 square miles of land, that is 49 people per square mile (19 per km²), placing Gallatin County #1,563 nationally for density and #3 in Montana. The median county equivalent has 47 people per square mile; the Montana median is 2.8. 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 Gallatin County

5 incorporated places lie at least partly in Gallatin County. Together they are home to 77,105 people (59.9%); the other 51,635 (40.1%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Bozeman city, with 58,814 residents in the county. Among places with at least 1,000 residents in 2020, Belgrade city grew fastest since then (+25.2%).

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

Metropolitan area

Gallatin County is a central county of the Bozeman, MT Metropolitan Statistical Area. Gallatin County is the area’s only county equivalent, so the metro area has the same 2,605.4 square miles of land. By combined land it ranks #124 of 393 metropolitan areas, and #323 by population.

ZIP codes

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

59086597145971559716597185973059741597525975859760

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 Gallatin County

Gallatin County shares a land border with 8 county equivalents, including 3 in Idaho and Wyoming. It has more land than 4 of them. The largest neighbor is Park County (6,939 mi²) and the smallest is Broadwater County (1,192.4 mi²). Together with its neighbors, Gallatin County forms a block of 27,037.1 mi² of land, of which it holds 9.6%.

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

Gallatin 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). Montana’s county land could hold about 56 areas the size of Gallatin County.

Another way to picture it: the same land area would fill a square about 51 miles (82.1 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 Gallatin County?

Gallatin County has more land than 3,018 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 Gallatin County at #217 nationally by total area, 13 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 1.1%, compared with a national county-equivalent median of 1.2%. The two percentages are within 0.1 percentage points of each other. 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 Gallatin 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.