County outline
Where Beaverhead County is located
Area breakdown
Land accounts for 99.5% of Beaverhead County’s measured area and water for 0.5%. Its combined area converts to 14,433.8 square kilometers or approximately 3,566,679 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 5,542.687 | 14,355.493 | 3,547,319.7 |
| Water | 30.249 | 78.345 | 19,359.4 |
| Total | 5,572.936 | 14,433.838 | 3,566,679 |
How Beaverhead County compares
By original Census land area, Beaverhead County ranks #1 of 56 in Montana and #65 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 2.345 times the Montana county-equivalent median of 2,363.3 square miles. It accounts for 3.8% of the combined county land area in the state.
See the complete Montana ranking · What counts as a county equivalent?
Population and density of Beaverhead County
The Census Bureau estimates that 10,043 people lived in Beaverhead County on July 1, 2025. That ranks #2,476 of 3,222 county equivalents nationally and #22 of 56 in Montana. Since the April 1, 2020 estimates base of 9,368, the population has grown by 675 (+7.2%), compared with +5.6% for Montana as a whole.
With 5,542.7 square miles of land, that is 1.8 people per square mile (0.7 per km²), placing Beaverhead County #3,082 nationally for density and #37 in Montana. The median county equivalent has 47 people per square mile; the Montana median is 2.8. Put another way, there are about 353 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 9,375 | 9,550 | 9,738 | 9,882 | 9,990 | 10,043 |
| Change | — | +175 | +188 | +144 | +108 | +53 |
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 Beaverhead County
2 incorporated places lie at least partly in Beaverhead County. Together they are home to 4,492 people (44.7%); the other 5,551 (55.3%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Dillon city, with 4,271 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Dillon cityCounty seat | 4,271 | +10.2% | 1.978 |
| Lima town | 221 | +5.7% | 0.559 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Beaverhead County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Beaverhead 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
10 ZIP Code Tabulation Areas have land in Beaverhead County; 8 of them have most of their land inside the county, and the others mainly cover neighboring areas.
59724597255972759732597365973959743597465976159762
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 Beaverhead County
Beaverhead County shares a land border with 7 county equivalents, including 3 in Idaho. It has more land than every one of them. The largest neighbor is Lemhi County (4,563.7 mi²) and the smallest is Silver Bow County (718 mi²). Together with its neighbors, Beaverhead County forms a block of 21,167.3 mi² of land, of which it holds 26.2%.
| Bordering county equivalent | Land mi² | Size vs. Beaverhead | Compare |
|---|---|---|---|
| Lemhi CountyIdaho | 4,563.7 | 1.2× smaller | Compare |
| Madison County | 3,588.2 | 1.5× smaller | Compare |
| Ravalli County | 2,391 | 2.3× smaller | Compare |
| Fremont CountyIdaho | 1,864 | 3× smaller | Compare |
| Clark CountyIdaho | 1,763.1 | 3.1× smaller | Compare |
| Deer Lodge County | 736.7 | 7.5× smaller | Compare |
| Silver Bow County | 718 | 7.7× smaller | Compare |
How big is Beaverhead County compared with U.S. states?
Beaverhead 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 1.2 times as much land (6,422.6 mi²). Montana’s county land could hold about 26 areas the size of Beaverhead County.
Another way to picture it: the same land area would fill a square about 74.4 miles (119.8 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 Beaverhead County?
Beaverhead County has more land than 3,157 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 Beaverhead County at #69 nationally by total area, 4 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 0.5%, 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 Beaverhead County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #64 | Box Elder County, Utah | 5,781.3 | Compare |
| #65 | Beaverhead County, Montana | 5,542.7 | This county |
| #66 | Lander County, Nevada | 5,519.2 | 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 45.133863, -112.892869. 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: 14,355,492,111 m²; AWATER: 78,345,288 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 Beaverhead County?
Beaverhead County, Montana has 5,542.7 square miles (14,355.5 km²) of land and 30.2 square miles of water, for a total area of 5,572.9 square miles. It ranks #65 of 3,222 U.S. county equivalents by land area.
Is Beaverhead County the largest county in Montana?
Yes. Beaverhead County has the most land of the 56 county equivalents in Montana.
What counties border Beaverhead County?
Beaverhead County shares a land border with Lemhi County, Idaho, Madison County, Clark County, Idaho, Deer Lodge County, Ravalli County, Silver Bow County, and Fremont County, Idaho.
What is the population of Beaverhead County?
The Census Bureau estimates Beaverhead County had 10,043 residents on July 1, 2025, ranking #2,476 of 3,222 county equivalents. That is 1.8 people per square mile of land.
What is the county seat of Beaverhead County?
The county seat of Beaverhead County is Dillon.
What cities and towns are in Beaverhead County?
Beaverhead County has 2 incorporated places. The most populous are Dillon city and Lima town; 5,551 residents live outside any incorporated place.
Is Beaverhead County part of a metropolitan area?
No. Beaverhead County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Beaverhead County?
10 ZIP Code Tabulation Areas have land in Beaverhead County, and 8 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Beaverhead 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 Beaverhead County?
The land measurement converts to approximately 3,547,320 acres. Including water, total area is approximately 3,566,679 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.