County outline
Where Rosebud County is located
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
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 5,008.135 | 12,971.01 | 3,205,206.4 |
| Water | 17.079 | 44.234 | 10,930.6 |
| Total | 5,025.214 | 13,015.245 | 3,216,137 |
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.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 8,309 | 8,076 | 8,107 | 8,112 | 8,218 | 8,253 |
| 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 place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Colstrip city | 2,091 | −0.5% | 4.046 |
| Forsyth cityCounty seat | 1,652 | −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%.
| Bordering county equivalent | Land mi² | Size vs. Rosebud | Compare |
|---|---|---|---|
| Big Horn County | 4,997.8 | about the same | Compare |
| Garfield County | 4,676.6 | 1.1× smaller | Compare |
| Custer County | 3,783.3 | 1.3× smaller | Compare |
| Powder River County | 3,298.2 | 1.5× smaller | Compare |
| Yellowstone County | 2,633.4 | 1.9× smaller | Compare |
| Musselshell County | 1,869 | 2.7× smaller | Compare |
| Petroleum County | 1,655.6 | 3× smaller | Compare |
| Treasure County | 977.8 | 5.1× smaller | Compare |
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.
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.
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 rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #77 | Douglas County, Oregon | 5,035.8 | Compare |
| #78 | Rosebud County, Montana | 5,008.1 | This county |
| #79 | Big Horn County, Montana | 4,997.8 | Compare |
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.
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.