2020 census
As of the 2020 census, the county had a population of 28,907. The median age was 48.1 years. 18.6% of residents were under the age of 18 and 24.7% of residents were 65 years of age or older. For every 100 females there were 97.6 males, and for every 100 females age 18 and over there were 95.5 males age 18 and over.[28]
The racial makeup of the county was 94.0% White, 0.3% Black or African American, 0.4% American Indian and Alaska Native, 0.4% Asian, <0.1% Native Hawaiian and Pacific Islander, 0.4% from some other race, and 4.3% from two or more races. Hispanic or Latino residents of any race comprised 1.4% of the population.[29]
53.4% of residents lived in urban areas, while 46.6% lived in rural areas.[30]
There were 12,901 households in the county, of which 22.4% had children under the age of 18 living in them. Of all households, 44.7% were married-couple households, 20.4% were households with a male householder and no spouse or partner present, and 26.4% were households with a female householder and no spouse or partner present. About 33.1% of all households were made up of individuals and 16.1% had someone living alone who was 65 years of age or older.[28]
There were 15,645 housing units, of which 17.5% were vacant. Among occupied housing units, 78.1% were owner-occupied and 21.9% were renter-occupied. The homeowner vacancy rate was 1.7% and the rental vacancy rate was 9.9%.[28]
2010 census
The 2010 United States census indicated Alpena County had a 2010 population of 29,598. This is a decrease of 1,716 people from 2000. Overall, the county had a -5.5% growth rate during this ten-year period. In 2010 there were 12,791 households and 8,164 families in the county. The population density was 51.8 per square mile (20.0 square kilometers).[31]
There were 16,053 housing units at an average density of 28.1 per square mile (10.8 square kilometers). Among the population at the time, 97.5% were White, 0.5% Native American, 0.5% Asian, 0.3% Black or African American, 0.1% of some other race and 1.1% of two or more races. 1.0% were Hispanic or Latino (of any race). 26.8% were of German, 19.5% Polish, 12.9% French, French Canadian or Cajun, 8.1% English, 6.4% Irish and 5.7% American ancestry.[31]
There were 12,791 households, out of which 25.3% had children under the age of 18 living with them, 50.0% were husband and wife families, 9.8% had a female householder with no husband present, 36.2% were non-families, and 30.8% were made up of individuals. The average household size was 2.27 and the average family size was 2.81.[31]
In the county, the population was spread out, with 20.9% under age of 18, 7.4% from 18 to 24, 20.8% from 25 to 44, 31.5% from 45 to 64, and 19.5% who were 65 years of age or older. The median age was 46 years. For every 100 females there were 96.4 males. For every 100 females age 18 and over, there were 94.1 males.[31]
The 2010 American Community Survey 3-year estimate indicated the median income for a household in the county was $36,242 and the median income for a family was $46,718. Males had a median income of $27,002 versus $15,670 for females. The per capita income for the county was $21,713. About 2.5% of families and 16.9% of the population were below the poverty line, including 27.2% of those under the age 18 and 10.0% of those age 65 or over.[31]