County outline
Where Alger County is located
Area breakdown
Land accounts for 18.1% of Alger County’s measured area and water for 81.9%. Its combined area converts to 13,073.4 square kilometers or approximately 3,230,518 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 915.04 | 2,369.943 | 585,625.6 |
| Water | 4,132.645 | 10,703.501 | 2,644,892.8 |
| Total | 5,047.685 | 13,073.444 | 3,230,518.4 |
How Alger County compares
By original Census land area, Alger County ranks #12 of 83 in Michigan and #805 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 1.611 times the Michigan county-equivalent median of 567.8 square miles. It accounts for 1.6% of the combined county land area in the state.
See the complete Michigan ranking · What counts as a county equivalent?
Population and density of Alger County
The Census Bureau estimates that 8,641 people lived in Alger County on July 1, 2025. That ranks #2,598 of 3,222 county equivalents nationally and #78 of 83 in Michigan. Since the April 1, 2020 estimates base of 8,839, the population has declined by 198 (−2.2%), compared with +0.5% for Michigan as a whole.
With 915 square miles of land, that is 9.4 people per square mile (3.6 per km²), placing Alger County #2,663 nationally for density and #78 in Michigan. The median county equivalent has 47 people per square mile; the Michigan median is 62. Put another way, there are about 68 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 8,845 | 8,777 | 8,782 | 8,753 | 8,707 | 8,641 |
| Change | — | −68 | +5 | −29 | −46 | −66 |
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 Alger County
Alger 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 Munising township, with 2,759 residents (31.9% of the county). The largest by land is Burt township, at 230.5 mi², or 25.2% of the county’s land.
| County subdivision | Population 2025 | Since 2020 | Land mi² | Share of county land |
|---|---|---|---|---|
| Munising townshipCounty seat | 2,759 | −4.2% | 202.2 | 22.1% |
| Munising cityCounty seat | 1,938 | −1.7% | 5.258 | 0.6% |
| Rock River township | 1,230 | −1.1% | 80.7 | 8.8% |
| Au Train township | 1,007 | −1.3% | 141.3 | 15.4% |
| Mathias township | 529 | −1.1% | 70.7 | 7.7% |
| Burt township | 401 | −1.2% | 230.5 | 25.2% |
| Limestone township | 378 | −1% | 74.2 | 8.1% |
| Onota township | 368 | −0.5% | 87.7 | 9.6% |
| Grand Island township | 31 | 0% | 22.5 | 2.5% |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Alger County. Land: 2026 Census Gazetteer. How communities are listed.
Metropolitan area
Alger 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
13 ZIP Code Tabulation Areas have land in Alger County; 9 of them have most of their land inside the county, and the others mainly cover neighboring areas.
49806498164982249825498264983949862498784988349884498854989149895
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 Alger County
Alger County shares a land border with 4 county equivalents. It has more land than 1 of them. The largest neighbor is Marquette County (1,809.1 mi²) and the smallest is Luce County (899.1 mi²). Together with its neighbors, Alger County forms a block of 5,966.2 mi² of land, of which it holds 15.3%.
| Bordering county equivalent | Land mi² | Size vs. Alger | Compare |
|---|---|---|---|
| Marquette County | 1,809.1 | 2× larger | Compare |
| Schoolcraft County | 1,171.9 | 1.3× larger | Compare |
| Delta County | 1,171.1 | 1.3× larger | Compare |
| Luce County | 899.1 | about the same | Compare |
How big is Alger County compared with U.S. states?
Alger County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.1 times as much. Michigan’s county land could hold about 62 areas the size of Alger County.
Another way to picture it: the same land area would fill a square about 30.2 miles (48.7 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 Alger County?
Alger County has more land than 2,417 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 Alger County at #84 nationally by total area, 721 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 81.9%, compared with a national county-equivalent median of 1.2% — 80.7 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 Alger County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #804 | Taylor County, Texas | 915.5 | Compare |
| #805 | Alger County, Michigan | 915 | This county |
| #806 | Martin County, Texas | 915 | 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 46.521736, -86.657119. 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: 2,369,943,218 m²; AWATER: 10,703,501,926 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 Alger County?
Alger County, Michigan has 915 square miles (2,369.9 km²) of land and 4,132.6 square miles of water, for a total area of 5,047.7 square miles. It ranks #805 of 3,222 U.S. county equivalents by land area.
Is Alger County the largest county in Michigan?
No. Alger County ranks #12 of 83 in Michigan by land area. The largest is Marquette County, with 1,809.1 square miles of land.
What counties border Alger County?
Alger County shares a land border with Schoolcraft County, Delta County, Marquette County, and Luce County.
What is the population of Alger County?
The Census Bureau estimates Alger County had 8,641 residents on July 1, 2025, ranking #2,598 of 3,222 county equivalents. That is 9.4 people per square mile of land.
What is the county seat of Alger County?
The county seat of Alger County is Munising.
What cities and towns are in Alger County?
Alger County has 9 county subdivisions (cities, towns and townships). The most populous five are Munising township, Munising city, Rock River township, Au Train township, and Mathias township.
Is Alger County part of a metropolitan area?
No. Alger County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Alger County?
13 ZIP Code Tabulation Areas have land in Alger 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 Alger County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.1 times as much land.
How many acres of land are in Alger County?
The land measurement converts to approximately 585,626 acres. Including water, total area is approximately 3,230,518 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.