Yellowstone County area

Population and density of Yellowstone County

The Census Bureau estimates that 172,692 people lived in Yellowstone County on July 1, 2025. That ranks #411 of 3,222 county equivalents nationally and #1 of 56 in Montana. Since the April 1, 2020 estimates base of 164,726, the population has grown by 7,966 (+4.8%), compared with +5.6% for Montana as a whole.

With 2,633.4 square miles of land, that is 66 people per square mile (25 per km²), placing Yellowstone County #1,313 nationally for density and #1 in Montana. The median county equivalent has 47 people per square mile; the Montana median is 2.8. Put another way, there are about 9.8 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 Yellowstone County

3 incorporated places lie at least partly in Yellowstone County. Together they are home to 128,580 people (74.5%); the other 44,112 (25.5%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Billings city, with 121,239 residents in the county. Among places with at least 1,000 residents in 2020, Billings city grew fastest since then (+3.5%).

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

Metropolitan area

Yellowstone County is a central county of the Billings, MT Metropolitan Statistical Area. Its 3 county equivalents have 193,603 residents on 6,477.8 square miles of land; Yellowstone County accounts for 40.7% of the land and 89.2% of the residents. By combined land it ranks #29 of 393 metropolitan areas, and #242 by population.

ZIP codes

16 ZIP Code Tabulation Areas have land in Yellowstone County; 12 of them have most of their land inside the county, and the others mainly cover neighboring areas.

59002590065901559024590375904159044590575906359064590795908859101591025910559106

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 Yellowstone County

Yellowstone County shares a land border with 7 county equivalents. It has more land than 5 of them. The largest neighbor is Rosebud County (5,008.1 mi²) and the smallest is Treasure County (977.8 mi²). Together with its neighbors, Yellowstone County forms a block of 20,504.9 mi² of land, of which it holds 12.8%.

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

Yellowstone County has more land than 2 of the 50 states. It is about 1.4 times the land area of Delaware (1,948.6 mi²), while Connecticut, the next larger state, has 1.8 times as much land (4,842.5 mi²). Montana’s county land could hold about 55 areas the size of Yellowstone County.

Another way to picture it: the same land area would fill a square about 51.3 miles (82.6 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 Yellowstone County?

Yellowstone County has more land than 3,020 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 Yellowstone County at #213 nationally by total area, 11 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 0.6%, compared with a national county-equivalent median of 1.2% — 0.6 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 Yellowstone 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.