County outline
Where Ontonagon County is located
Area breakdown
Land accounts for 35% of Ontonagon County’s measured area and water for 65%. Its combined area converts to 9,687.7 square kilometers or approximately 2,393,882 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 1,310.978 | 3,395.417 | 839,025.9 |
| Water | 2,429.463 | 6,292.28 | 1,554,856.3 |
| Total | 3,740.441 | 9,687.698 | 2,393,882.2 |
How Ontonagon County compares
By original Census land area, Ontonagon County ranks #3 of 83 in Michigan and #455 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 2.309 times the Michigan county-equivalent median of 567.8 square miles. It accounts for 2.3% of the combined county land area in the state.
See the complete Michigan ranking · What counts as a county equivalent?
Population and density of Ontonagon County
The Census Bureau estimates that 5,823 people lived in Ontonagon County on July 1, 2025. That ranks #2,822 of 3,222 county equivalents nationally and #82 of 83 in Michigan. Since the April 1, 2020 estimates base of 5,807, the population has grown by 16 (+0.3%), compared with +0.5% for Michigan as a whole.
With 1,311 square miles of land, that is 4.4 people per square mile (1.7 per km²), placing Ontonagon County #2,871 nationally for density and #82 in Michigan. The median county equivalent has 47 people per square mile; the Michigan median is 62. Put another way, there are about 144 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 5,799 | 5,868 | 5,889 | 5,880 | 5,866 | 5,823 |
| Change | — | +69 | +21 | −9 | −14 | −43 |
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 Ontonagon County
Ontonagon County is divided into 11 municipalities and townships. In Michigan, county subdivisions are local governments, and together they cover all of the county’s land and residents.
The most populous is Ontonagon township, with 2,277 residents (39.1% of the county). The largest by land is Carp Lake township, at 226 mi², or 17.2% of the county’s land.
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Ontonagon townshipCounty seat | 2,277 | +1% | 193.8 | 14.8% |
| Stannard township | 639 | −0.5% | 124.9 | 9.5% |
| Greenland township | 624 | −1.3% | 112.6 | 8.6% |
| Carp Lake township | 583 | +0.5% | 226 | 17.2% |
| Bergland township | 443 | +1.4% | 97.5 | 7.4% |
| McMillan township | 405 | −1% | 70.9 | 5.4% |
| Interior township | 269 | −0.4% | 86.4 | 6.6% |
| Rockland township | 223 | +0.5% | 92.9 | 7.1% |
| Haight township | 205 | 0% | 105.6 | 8.1% |
| Matchwood township | 83 | 0% | 108.8 | 8.3% |
| Bohemia township | 72 | 0% | 91.7 | 7% |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Ontonagon County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Ontonagon 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 Ontonagon County; 8 of them have most of their land inside the county, and the others mainly cover neighboring areas.
499104991249925499294994749948499524995349960499654996749971
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 Ontonagon County
Ontonagon County shares a land border with 3 county equivalents. It has more land than every one of them. The largest neighbor is Iron County (1,166.1 mi²) and the smallest is Houghton County (1,009.1 mi²). Together with its neighbors, Ontonagon County forms a block of 4,588.3 mi² of land, of which it holds 28.6%.
| Bordering county equivalent | Land mi² | Size vs. Ontonagon | Compare |
|---|---|---|---|
| Iron County | 1,166.1 | 1.1× smaller | Compare |
| Gogebic County | 1,102.1 | 1.2× smaller | Compare |
| Houghton County | 1,009.1 | 1.3× smaller | Compare |
How big is Ontonagon County compared with U.S. states?
Ontonagon County has more land than 1 of the 50 states. It is about 1.3 times the land area of Rhode Island (1,033.9 mi²), while Delaware, the next larger state, has 1.5 times as much land (1,948.6 mi²). Michigan’s county land could hold about 43 areas the size of Ontonagon County.
Another way to picture it: the same land area would fill a square about 36.2 miles (58.3 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 Ontonagon County?
Ontonagon County has more land than 2,767 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 Ontonagon County at #145 nationally by total area, 310 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.
Its water share is 65%, compared with a national county-equivalent median of 1.2% — 63.8 percentage points higher. 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 Ontonagon County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #454 | Glenn County, California | 1,313.9 | Compare |
| #455 | Ontonagon County, Michigan | 1,311 | This county |
| #456 | Schleicher County, Texas | 1,310.6 | 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 46.835203, -89.276943. 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: 3,395,416,339 m²; AWATER: 6,292,279,170 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 Ontonagon County?
Ontonagon County, Michigan has 1,311 square miles (3,395.4 km²) of land and 2,429.5 square miles of water, for a total area of 3,740.4 square miles. It ranks #455 of 3,222 U.S. county equivalents by land area.
Is Ontonagon County the largest county in Michigan?
No. Ontonagon County ranks #3 of 83 in Michigan by land area. The largest is Marquette County, with 1,809.1 square miles of land.
What counties border Ontonagon County?
Ontonagon County shares a land border with Gogebic County, Houghton County, and Iron County.
What is the population of Ontonagon County?
The Census Bureau estimates Ontonagon County had 5,823 residents on July 1, 2025, ranking #2,822 of 3,222 county equivalents. That is 4.4 people per square mile of land.
What is the county seat of Ontonagon County?
The county seat of Ontonagon County is Ontonagon.
What cities and towns are in Ontonagon County?
Ontonagon County has 11 county subdivisions (cities, towns and townships). The most populous five are Ontonagon township, Stannard township, Greenland township, Carp Lake township, and Bergland township.
Is Ontonagon County part of a metropolitan area?
No. Ontonagon County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Ontonagon County?
12 ZIP Code Tabulation Areas have land in Ontonagon 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 Ontonagon County compare with U.S. states?
It has more land than 1 of the 50 states, including Rhode Island (1,033.9 square miles of land).
How many acres of land are in Ontonagon County?
The land measurement converts to approximately 839,026 acres. Including water, total area is approximately 2,393,882 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.