Iosco County (/aɪˈɒskoʊ/ eye-OSS-koh) is a county in the U.S. state of Michigan; its eastern border is formed by Lake Huron. As of the 2020 census, its population was 25,237. Its seat of government is Tawas City.

Iosco has traditionally been said to be a Native American word meaning "water of light", but was actually coined as a pseudo-Native American name by Henry Rowe Schoolcraft, an American geographer and ethnologist who served as the U.S. Indian agent in Michigan in the late 19th century. He named several counties and towns during the state's formative years.

The county was created by the Michigan Legislature in 1840 as Kanotin County, and renamed Iosco County in 1843. It was administered by a succession of other Michigan counties before the organization of county government in 1857. A majority of the population was Ojibwe. The area offered shelter from tall white pines and food from the river and lake. Iosco County was cut from a piece of land ceded by the Ojibwe to the U.S. government. When the lumber boom hit, many more people moved to the area.

The 400-acre Alabaster Historic District, listed on the National Register of Historic Places, is associated with an operating gypsum open-pit mine south of Tawas City. The large company town included internal rail lines for transportation and a tramway extending over Lake Huron on long piers for loading gypsum onto ships. Started in 1862, the mine supplied gypsum for temporary buildings constructed in Chicago at the World Columbian Exposition of 1893. Two companies continue to mine gypsum in Iosco County.

In 2009, Alabaster Township formed the nonprofit Alabaster Wind Power Development Corp. to conduct the necessary two-year studies of wind data at this site as a potential location for development of wind turbines. It proposed using 10 large tramway platforms that extend more than 6,000 feet into the lake to gauge winds. The turbines could be built on the tramways. At the time, the federal government was offering subsidies for such studies and development of alternative energy projects.

According to the US Census Bureau, the county has an area of 1,890 square miles (4,900 km), of which 549 square miles (1,420 km) is land and 1,341 square miles (3,470 km) (71%) is water. It is considered part of Northern Michigan. In total, it covers about 6,361,837 acres.

• Lumberman's Monument
• Canoer's memorial
• 60 Lakes Area - Located near Hale
• Iargo Springs
• Tawas Point Light House - First lit in 1853
• Tawas Bay
• Pine River – rises in Alcona County and flows into Iosco County, where it empties into Van Etten Lake at 44°29′38″N 83°23′16″W / 44.49389°N 83.38778°W / 44.49389; -83.38778 northwest of Oscoda.
• Au Sable River
• Tuttle Marsh Wildlife Area
• Van Etten Lake
• Tawas Lake
• Foote Dam Pond
• Au Sable State Forest (partial) – the Grayling Fire Management Unit consists of Alcona, Crawford, and Oscoda Counties, and northern Iosco county.

• US 23 – known as the Sunrise Side Coastal Highway.
• M-55 – one of three cross-peninsular state highways. It begins in Tawas City at the junction with US 23.
• M-65
• F-41
• River Road National Scenic Byway – starts at M-65 and runs parallel with the Au Sable River for 23 miles (37 km) eastward to US 23 in Oscoda, Michigan. It is a designated National Scenic Byway. It passes the Lumberman's Monument.

By land

• Alcona County - north
• Arenac County - southwest
• Ogemaw County - west
• Oscoda County - northwest

By water

• Huron County - southeast

• Huron National Forest (part)

• East Tawas
• Tawas City (county seat)
• Whittemore

• Au Sable Charter Township
• Oscoda Charter Township

• Au Sable
• Oscoda
• Sand Lake

• Alabaster
• Foote Site Village
• Hale
• Long Lake
• National City
• South Branch

Historical population

Census	Pop.	Note	%±
1860	175		—
1870	3,163		1,707.4%
1880	6,873		117.3%
1890	15,224		121.5%
1900	10,246		−32.7%
1910	9,753		−4.8%
1920	8,199		−15.9%
1930	7,517		−8.3%
1940	8,560		13.9%
1950	10,906		27.4%
1960	16,505		51.3%
1970	24,905		50.9%
1980	28,349		13.8%
1990	30,209		6.6%
2000	27,339		−9.5%
2010	25,887		−5.3%
2020	25,237		−2.5%
2023 (est.)	25,373		0.5%
US Decennial Census 1790-1960 1900-1990 1990-2000 2010-2018

As of the 2000 United States census, there were 27,339 people, 11,727 households, and 7,857 families in the county. Most of the population is located on the shoreline along US-23,East Tawas, Tawas City, and Oscoda County. The population density was 50 people per square mile (19 people/km). There were 20,432 housing units at an average density of 37 per square mile (14/km). By the 2020 census, its population was 25,237.

In 2000, the county's racial makeup was 96.92% White, 0.41% Black or African American, 0.66% Native American, 0.46% Asian, 0.05% Pacific Islander, 0.23% from other races, and 1.27% from two or more races. 0.98% of the population were Hispanic or Latino of any race. 23.2% were of German, 12.3% English, 10.6% Irish, 9.9% American, 8.3% Polish and 7.1% French ancestry. 97.4% spoke English and 1.0% Spanish as their first language.

There were 11,727 households, out of which 24.90% had children under the age of 18 living with them, 55.20% were married couples living together, 8.40% had a female householder with no husband present, and 33.00% were non-families. 28.60% of all households were made up of individuals, and 14.00% had someone living alone who was 65 years of age or older. The average household size was 2.30 and the average family size was 2.79.

The county population included 22.40% under the age of 18, 5.40% from 18 to 24, 23.40% from 25 to 44, 27.30% from 45 to 64, and 21.60% who were 65 years of age or older. The median age was 44 years. For every 100 females there were 96.30 males. For every 100 females age 18 and over, there were 93.60 males.

In 2000, the median income for a household in the county was $31,321, and the median income for a family was $37,452. Males had a median income of $30,338 versus $21,149 for females. The per capita income for the county was $17,115. About 9.50% of families and 12.70% of the population were below the poverty line, including 18.50% of those under age 18 and 7.60% of those age 65 or over.

The county government operates the jail, maintains rural roads, operates the major local courts, records deeds, mortgages, and vital records, administers public health regulations, and participates with the state in the provision of social services. The county board of commissioners controls the budget, with limited authority to make laws or ordinances. In Michigan, most local government functions—police and fire, building and zoning tax assessment, street maintenance, etc.—are the responsibility of individual cities and townships.

Iosco County has been reliably Republican from the beginning. Since 1884, the Republican presidential nominee has carried the county in 27 of 35 elections.

United States presidential election results for Iosco County, Michigan

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	9,759	63.42%	5,373	34.92%	255	1.66%
2016	8,345	62.14%	4,345	32.36%	739	5.50%
2012	6,909	51.62%	6,242	46.63%	234	1.75%
2008	6,583	46.28%	7,309	51.38%	333	2.34%
2004	7,301	52.13%	6,557	46.82%	148	1.06%
2000	6,345	47.99%	6,505	49.20%	372	2.81%
1996	4,410	35.50%	6,240	50.23%	1,774	14.28%
1992	4,912	36.41%	5,369	39.79%	3,211	23.80%
1988	7,234	59.17%	4,929	40.32%	62	0.51%
1984	7,907	66.99%	3,850	32.62%	47	0.40%
1980	6,680	56.54%	4,255	36.01%	880	7.45%
1976	5,500	52.39%	4,875	46.44%	123	1.17%
1972	5,750	64.10%	3,065	34.17%	156	1.74%
1968	4,068	55.42%	2,533	34.51%	739	10.07%
1964	2,704	38.39%	4,336	61.56%	4	0.06%
1960	4,308	62.74%	2,549	37.12%	9	0.13%
1956	4,385	72.50%	1,660	27.45%	3	0.05%
1952	3,772	74.56%	1,274	25.18%	13	0.26%
1948	2,599	68.90%	1,115	29.56%	58	1.54%
1944	2,340	67.26%	1,127	32.39%	12	0.34%
1940	2,504	65.46%	1,303	34.07%	18	0.47%
1936	1,768	50.88%	1,547	44.52%	160	4.60%
1932	1,581	49.62%	1,500	47.08%	105	3.30%
1928	1,873	76.79%	552	22.63%	14	0.57%
1924	1,713	71.43%	304	12.68%	381	15.89%
1920	2,013	76.71%	548	20.88%	63	2.40%
1916	984	56.00%	729	41.49%	44	2.50%
1912	521	28.90%	418	23.18%	864	47.92%
1908	1,224	63.03%	668	34.40%	50	2.57%
1904	1,482	75.30%	426	21.65%	60	3.05%
1900	1,402	66.41%	679	32.16%	30	1.42%
1896	1,470	60.25%	912	37.38%	58	2.38%
1892	1,393	49.57%	1,336	47.54%	81	2.88%
1888	1,505	45.45%	1,639	49.50%	167	5.04%
1884	1,016	52.83%	864	44.93%	43	2.24%

• Prosecuting Attorney: James Bacarella
• Sheriff: Scott D. Frank
• County Clerk: Nancy J. Huebel
• County Treasurer: Cathy Anderson
• Register of Deeds: Ericka Earl
• Drain Commissioner: Fred Strauer

County commissioners

• District 1: Robert Huebel III
• District 2: Terry Dutcher
• District 3: Charles Finley
• District 4: John Moehring
• District 5: Donald "Jay" O'Farrell

Iosco County has four public school districts:

• Hale Area Schools
• Oscoda Area Schools
• Tawas Area Schools
• Whittemore-Prescott Area Schools

There are also three private elementary schools:

• Emanuel Lutheran School (Tawas City)
• Holy Family School (East Tawas)
• Shady Grove School (Whittemore)

Alpena Community College offers college-level courses at its campus on the former Wurtsmith Air Force Base in Oscoda and local public school facilities.

• The Iosco County News-Herald is the newspaper of record for Iosco County.
• The Oscoda Press is a weekly newspaper serving northern Iosco County and southern Alcona County.

• List of Michigan State Historic Sites in Iosco County, Michigan
• National Register of Historic Places listings in Iosco County, Michigan

• Romig, Walter (1986) [1973]. Michigan Place Names: The History of the Founding and the Naming of More than Five Thousand Past and Present Michigan Communities. Great Lakes Books. Detroit: Wayne State University Press. ISBN 978-0814318386.

• "Bibliography on Iosco County". Clarke Historical Library, Central Michigan University.
• County of Iosco, links, media, history, parks, and services
• Enchanted forest, Northern Michigan source for information, calendars, etc.
• Iosco County website

44°17′N 83°20′W / 44.28°N 83.34°W / 44.28; -83.34