Rosebud County area

Rosebud County, Montana covers 5,025.2 square miles: 5,008.1 square miles of land and 17.1 square miles of water. Its county seat is Forsyth. An estimated 8,253 people lived there in 2025.

Official Census measurements · GEOID 300872026 Gazetteer · retrieved September 27, 2026
Land area5,008.1 mi²
Water area17.1 mi²
Population (2025)8,253
People per mi²1.6

County outline

Generalized outline of Rosebud County, Montana
2025 Census cartographic boundary, fitted to this frame. County maps are not at a common scale. The 2026 area measurements below come from the separate Gazetteer release. Map source and limitations.

Where Rosebud County is located

Rosebud County highlighted on a map of all U.S. county equivalents. About the maps

Area breakdown

Land accounts for 99.7% of Rosebud County’s measured area and water for 0.3%. Its combined area converts to 13,015.2 square kilometers or approximately 3,216,137 acres.

Green: land · blue: water

MeasurementSquare milesSquare kilometersAcres
Land5,008.13512,971.013,205,206.4
Water17.07944.23410,930.6
Total5,025.21413,015.2453,216,137

How Rosebud County compares

By original Census land area, Rosebud County ranks #4 of 56 in Montana and #78 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.

Its land area is 2.119 times the Montana county-equivalent median of 2,363.3 square miles. It accounts for 3.4% of the combined county land area in the state.

See the complete Montana ranking · What counts as a county equivalent?

Population and density of Rosebud County

The Census Bureau estimates that 8,253 people lived in Rosebud County on July 1, 2025. That ranks #2,631 of 3,222 county equivalents nationally and #28 of 56 in Montana. Since the April 1, 2020 estimates base of 8,335, the population has declined by 82 (−1%), compared with +5.6% for Montana as a whole.

With 5,008.1 square miles of land, that is 1.6 people per square mile (0.64 per km²), placing Rosebud County #3,094 nationally for density and #38 in Montana. The median county equivalent has 47 people per square mile; the Montana median is 2.8. Put another way, there are about 388 acres of land per resident.

Estimated population, 2020–2025 · line scaled to this county’s own range
July 1202020212022202320242025
Estimate8,3098,0768,1078,1128,2188,253
Change—−233+31+5+106+35

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 Rosebud County

2 incorporated places lie at least partly in Rosebud County. Together they are home to 3,743 people (45.4%); the other 4,510 (54.6%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Colstrip city, with 2,091 residents in the county. The county seat, Forsyth city, has 1,652 residents.

Incorporated placePopulation 2025Since 2020Land mi²
Colstrip city2,091−0.5%4.046
Forsyth cityCounty seat1,652−1.5%1.151

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

Metropolitan area

Rosebud County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.

ZIP codes

12 ZIP Code Tabulation Areas have land in Rosebud County; 9 of them have most of their land inside the county, and the others mainly cover neighboring areas.

590035901259039590435905459062590835930159323593275933359347

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 Rosebud County

Rosebud County shares a land border with 8 county equivalents. It has more land than every one of them. The largest neighbor is Big Horn County (4,997.8 mi²) and the smallest is Treasure County (977.8 mi²). Together with its neighbors, Rosebud County forms a block of 28,899.8 mi² of land, of which it holds 17.3%.

Map of Rosebud County and the 8 county equivalents that border it Garfield County, Montana: 4,676.6 mi² landBig Horn County, Montana: 4,997.8 mi² landTreasure County, Montana: 977.8 mi² landCuster County, Montana: 3,783.3 mi² landPowder River County, Montana: 3,298.2 mi² landMusselshell County, Montana: 1,869 mi² landPetroleum County, Montana: 1,655.6 mi² landYellowstone County, Montana: 2,633.4 mi² land
Rosebud County (dark) and its bordering county equivalents. Select a neighbor to open its profile. Drawn from the 2025 Census cartographic boundaries in an equal-area projection. How borders are determined.
Bordering county equivalentLand mi²Size vs. RosebudCompare
Big Horn County4,997.8about the sameCompare
Garfield County4,676.61.1× smallerCompare
Custer County3,783.31.3× smallerCompare
Powder River County3,298.21.5× smallerCompare
Yellowstone County2,633.41.9× smallerCompare
Musselshell County1,8692.7× smallerCompare
Petroleum County1,655.63× smallerCompare
Treasure County977.85.1× smallerCompare

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

Rosebud County has more land than 3 of the 50 states. It is about 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 Rosebud County.

Land area: Rosebud County and the closest-sized states
Connecticut4,842.5 mi²
Rosebud County5,008.1 mi²
Hawaii6,422.6 mi²

Another way to picture it: the same land area would fill a square about 70.8 miles (113.9 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 Rosebud County?

Rosebud County has more land than 3,144 of the other 3,221 county equivalents in the dataset.

Land area compared with the typical county equivalent
Rosebud County5,008.1 mi²
Montana median2,363.3 mi²
National median604.5 mi²

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 Rosebud County at #85 nationally by total area, 7 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 0.3%, compared with a national county-equivalent median of 1.2% — 0.8 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 Rosebud County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Land rankCounty equivalentLand mi²Comparison
#77Douglas County, Oregon5,035.8Compare
#78Rosebud County, Montana5,008.1This county
#79Big Horn County, Montana4,997.8Compare

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.

Representative coordinates

The Census internal point is 46.173226, -106.666636. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.

Source and precision

U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 12,971,010,119 m²; AWATER: 44,234,227 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.

Download the official county source ZIP ↗ · Methodology

Common questions

How big is Rosebud County?

Rosebud County, Montana has 5,008.1 square miles (12,971 km²) of land and 17.1 square miles of water, for a total area of 5,025.2 square miles. It ranks #78 of 3,222 U.S. county equivalents by land area.

Is Rosebud County the largest county in Montana?

No. Rosebud County ranks #4 of 56 in Montana by land area. The largest is Beaverhead County, with 5,542.7 square miles of land.

What counties border Rosebud County?

Rosebud County shares a land border with Garfield County, Big Horn County, Treasure County, Custer County, Powder River County, Musselshell County, Petroleum County, and Yellowstone County.

What is the population of Rosebud County?

The Census Bureau estimates Rosebud County had 8,253 residents on July 1, 2025, ranking #2,631 of 3,222 county equivalents. That is 1.6 people per square mile of land.

What is the county seat of Rosebud County?

The county seat of Rosebud County is Forsyth.

What cities and towns are in Rosebud County?

Rosebud County has 2 incorporated places. The most populous are Colstrip city and Forsyth city; 4,510 residents live outside any incorporated place.

Is Rosebud County part of a metropolitan area?

No. Rosebud County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.

How many ZIP codes are in Rosebud County?

12 ZIP Code Tabulation Areas have land in Rosebud County, and 9 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.

How does Rosebud County compare with U.S. states?

It has more land than 3 of the 50 states, including Connecticut (4,842.5 square miles of land).

How many acres of land are in Rosebud County?

The land measurement converts to approximately 3,205,206 acres. Including water, total area is approximately 3,216,137 acres. One square mile equals 640 acres.

Why might another source show a different area?

Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.

Can this establish a property boundary?

No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.

Cite this county

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