County outline
Where Sanders County is located
Area breakdown
Land accounts for 98.9% of Sanders County’s measured area and water for 1.1%. Its combined area converts to 7,225.8 square kilometers or approximately 1,785,534 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 2,760.401 | 7,149.406 | 1,766,656.6 |
| Water | 29.496 | 76.394 | 18,877.4 |
| Total | 2,789.897 | 7,225.8 | 1,785,534.1 |
How Sanders County compares
By original Census land area, Sanders County ranks #20 of 56 in Montana and #188 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.168 times the Montana county-equivalent median of 2,363.3 square miles. It accounts for 1.9% of the combined county land area in the state.
See the complete Montana ranking · What counts as a county equivalent?
Population and density of Sanders County
The Census Bureau estimates that 14,062 people lived in Sanders County on July 1, 2025. That ranks #2,228 of 3,222 county equivalents nationally and #13 of 56 in Montana. Since the April 1, 2020 estimates base of 12,395, the population has grown by 1,667 (+13.4%), compared with +5.6% for Montana as a whole.
With 2,760.4 square miles of land, that is 5.1 people per square mile (2 per km²), placing Sanders County #2,849 nationally for density and #19 in Montana. The median county equivalent has 47 people per square mile; the Montana median is 2.8. Put another way, there are about 126 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 12,454 | 12,933 | 13,373 | 13,713 | 13,892 | 14,062 |
| Change | — | +479 | +440 | +340 | +179 | +170 |
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 Sanders County
3 incorporated places lie at least partly in Sanders County. Together they are home to 3,434 people (24.4%); the other 10,628 (75.6%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Thompson Falls city, with 1,543 residents in the county. Among places with at least 1,000 residents in 2020, Plains town grew fastest since then (+13.6%).
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Thompson Falls cityCounty seat | 1,543 | +13.5% | 1.604 |
| Plains town | 1,261 | +13.6% | 0.615 |
| Hot Springs town | 630 | +12.5% | 0.478 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Sanders County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Sanders 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
11 ZIP Code Tabulation Areas have land in Sanders County; 9 of them have most of their land inside the county, and the others mainly cover neighboring areas.
5982159831598445984559848598535985659859598665987359874
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 Sanders County
Sanders County shares a land border with 7 county equivalents, including 2 in Idaho. It has more land than 5 of them. The largest neighbor is Flathead County (5,087.3 mi²) and the smallest is Mineral County (1,219.6 mi²). Together with its neighbors, Sanders County forms a block of 21,134.2 mi² of land, of which it holds 13.1%.
| Bordering county equivalent | Land mi² | Size vs. Sanders | Compare |
|---|---|---|---|
| Flathead County | 5,087.3 | 1.8× larger | Compare |
| Lincoln County | 3,612.6 | 1.3× larger | Compare |
| Shoshone CountyIdaho | 2,637.5 | about the same | Compare |
| Missoula County | 2,593 | 1.1× smaller | Compare |
| Bonner CountyIdaho | 1,733.2 | 1.6× smaller | Compare |
| Lake County | 1,490.5 | 1.9× smaller | Compare |
| Mineral County | 1,219.6 | 2.3× smaller | Compare |
How big is Sanders County compared with U.S. states?
Sanders 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 53 areas the size of Sanders County.
Another way to picture it: the same land area would fill a square about 52.5 miles (84.6 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 Sanders County?
Sanders County has more land than 3,034 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 Sanders County at #203 nationally by total area, 15 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% — 0.1 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 Sanders County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #187 | Pennington County, South Dakota | 2,776.8 | Compare |
| #188 | Sanders County, Montana | 2,760.4 | This county |
| #189 | McKenzie County, North Dakota | 2,760.1 | 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 47.756497, -115.180306. 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: 7,149,405,615 m²; AWATER: 76,393,633 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 Sanders County?
Sanders County, Montana has 2,760.4 square miles (7,149.4 km²) of land and 29.5 square miles of water, for a total area of 2,789.9 square miles. It ranks #188 of 3,222 U.S. county equivalents by land area.
Is Sanders County the largest county in Montana?
No. Sanders County ranks #20 of 56 in Montana by land area. The largest is Beaverhead County, with 5,542.7 square miles of land.
What counties border Sanders County?
Sanders County shares a land border with Lincoln County, Lake County, Mineral County, Shoshone County, Idaho, Flathead County, Missoula County, and Bonner County, Idaho.
What is the population of Sanders County?
The Census Bureau estimates Sanders County had 14,062 residents on July 1, 2025, ranking #2,228 of 3,222 county equivalents. That is 5.1 people per square mile of land.
What is the county seat of Sanders County?
The county seat of Sanders County is Thompson Falls.
What cities and towns are in Sanders County?
Sanders County has 3 incorporated places. The most populous are Thompson Falls city, Plains town, and Hot Springs town; 10,628 residents live outside any incorporated place.
Is Sanders County part of a metropolitan area?
No. Sanders County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Sanders County?
11 ZIP Code Tabulation Areas have land in Sanders 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 Sanders County compare with U.S. states?
It has more land than 2 of the 50 states, including Delaware (1,948.6 square miles of land).
How many acres of land are in Sanders County?
The land measurement converts to approximately 1,766,657 acres. Including water, total area is approximately 1,785,534 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.