County outline
Where Alpena County is located
Area breakdown
Land accounts for 33.7% of Alpena County’s measured area and water for 66.3%. Its combined area converts to 4,389.8 square kilometers or approximately 1,084,753 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 571.899 | 1,481.212 | 366,015.4 |
| Water | 1,123.027 | 2,908.627 | 718,737.3 |
| Total | 1,694.926 | 4,389.838 | 1,084,752.6 |
How Alpena County compares
By original Census land area, Alpena County ranks #39 of 83 in Michigan and #1754 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.007 times the Michigan county-equivalent median of 567.8 square miles. It accounts for 1% of the combined county land area in the state.
See the complete Michigan ranking · What counts as a county equivalent?
Population and density of Alpena County
The Census Bureau estimates that 28,853 people lived in Alpena County on July 1, 2025. That ranks #1,523 of 3,222 county equivalents nationally and #50 of 83 in Michigan. Since the April 1, 2020 estimates base of 28,916, the population has declined by 63 (−0.2%), compared with +0.5% for Michigan as a whole.
With 571.9 square miles of land, that is 50 people per square mile (19 per km²), placing Alpena County #1,548 nationally for density and #51 in Michigan. The median county equivalent has 47 people per square mile; the Michigan median is 62. Put another way, there are about 13 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 28,891 | 28,953 | 28,827 | 28,868 | 28,883 | 28,853 |
| Change | — | +62 | −126 | +41 | +15 | −30 |
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 Alpena County
Alpena County is divided into 9 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 Alpena city, with 10,088 residents (35% of the county). The largest by land is Ossineke township, at 105.7 mi², or 18.5% of the county’s land. Among those with at least 1,000 residents in 2020, Green township grew fastest since then (+2%).
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Alpena cityCounty seat | 10,088 | −1.5% | 8.172 | 1.4% |
| Alpena townshipCounty seat | 9,068 | −0.1% | 104.8 | 18.3% |
| Sanborn township | 2,099 | +0.7% | 43.8 | 7.7% |
| Wilson township | 1,987 | +0.2% | 79.3 | 13.9% |
| Ossineke township | 1,650 | +0.9% | 105.7 | 18.5% |
| Maple Ridge township | 1,589 | +1.5% | 51.6 | 9% |
| Green township | 1,132 | +2% | 71.1 | 12.4% |
| Long Rapids township | 987 | +0.9% | 54.2 | 9.5% |
| Wellington township | 253 | +2.4% | 53.2 | 9.3% |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Alpena County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Alpena County is a central county of the Alpena, MI Micropolitan Statistical Area. Alpena County is the area’s only county equivalent, so the micro area has the same 571.9 square miles of land. By combined land it ranks #374 of 542 micropolitan areas, and #450 by population.
ZIP codes
8 ZIP Code Tabulation Areas have land in Alpena County; 4 of them have most of their land inside the county, and the others mainly cover neighboring areas.
4876249707497444974649747497534976649776
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 Alpena County
Alpena County shares a land border with 3 county equivalents. It has more land than 1 of them. The largest neighbor is Alcona County (674.7 mi²) and the smallest is Montmorency County (546.7 mi²). Together with its neighbors, Alpena County forms a block of 2,451.9 mi² of land, of which it holds 23.3%.
| Bordering county equivalent | Land mi² | Size vs. Alpena | Compare |
|---|---|---|---|
| Alcona County | 674.7 | 1.2× larger | Compare |
| Presque Isle County | 658.7 | 1.2× larger | Compare |
| Montmorency County | 546.7 | about the same | Compare |
How big is Alpena County compared with U.S. states?
Alpena County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.8 times as much. Michigan’s county land could hold about 99 areas the size of Alpena County.
Another way to picture it: the same land area would fill a square about 23.9 miles (38.5 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 Alpena County?
Alpena County has more land than 1,468 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 Alpena County at #397 nationally by total area, 1,357 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 66.3%, compared with a national county-equivalent median of 1.2% — 65.1 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 Alpena County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1753 | Clay County, Nebraska | 572.3 | Compare |
| #1754 | Alpena County, Michigan | 571.9 | This county |
| #1755 | St. Lucie County, Florida | 571.9 | 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 44.894948, -83.426591. 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: 1,481,211,821 m²; AWATER: 2,908,626,556 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 Alpena County?
Alpena County, Michigan has 571.9 square miles (1,481.2 km²) of land and 1,123 square miles of water, for a total area of 1,694.9 square miles. It ranks #1754 of 3,222 U.S. county equivalents by land area.
Is Alpena County the largest county in Michigan?
No. Alpena County ranks #39 of 83 in Michigan by land area. The largest is Marquette County, with 1,809.1 square miles of land.
What counties border Alpena County?
Alpena County shares a land border with Alcona County, Presque Isle County, and Montmorency County.
What is the population of Alpena County?
The Census Bureau estimates Alpena County had 28,853 residents on July 1, 2025, ranking #1,523 of 3,222 county equivalents. That is 50 people per square mile of land.
What is the county seat of Alpena County?
The county seat of Alpena County is Alpena.
What cities and towns are in Alpena County?
Alpena County has 9 county subdivisions (cities, towns and townships). The most populous five are Alpena city, Alpena township, Sanborn township, Wilson township, and Ossineke township.
Is Alpena County part of a metropolitan area?
Yes. It is a central county of the Alpena, MI Micropolitan Statistical Area.
How many ZIP codes are in Alpena County?
8 ZIP Code Tabulation Areas have land in Alpena County, and 4 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Alpena County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.8 times as much land.
How many acres of land are in Alpena County?
The land measurement converts to approximately 366,015 acres. Including water, total area is approximately 1,084,753 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.