A post office called McKinley was established in 1892, and remained in operation until 1991. The city was named for three McKinley brothers who were businessmen in the mining industry. McKinley was incorporated in 1892.
As of the census of 2010, there were 128 people, 56 households, and 36 families living in the city. The population density was. There were 67 housing units at an average density of. The racial makeup of the city was 93.8% White, 4.7% from other races, and 1.6% from two or more races. Hispanic or Latino of any race were 6.3% of the population. There were 56 households of which 28.6% had children under the age of 18 living with them, 48.2% were married couplesliving together, 12.5% had a female householder with no husband present, 3.6% had a male householder with no wife present, and 35.7% were non-families. 32.1% of all households were made up of individuals and 21.4% had someone living alone who was 65 years of age or older. The average household size was 2.29 and the average family size was 2.92. The median age in the city was 42.5 years. 25.8% of residents were under the age of 18; 5.5% were between the ages of 18 and 24; 19.5% were from 25 to 44; 29.7% were from 45 to 64; and 19.5% were 65 years of age or older. The gender makeup of the city was 43.8% male and 56.3% female.
2000 census
As of the census of 2000, there were 80 people, 37 households, and 25 families living in the city. The population density was 103.3 people per square mile. There were 43 housing units at an average density of 55.5 per square mile. The racial makeup of the city was 97.50% White, and 2.50% from two or more races. 28.6% were of Slovene, 14.3% German, 11.9% English, 9.5% Norwegian and 7.1% Austrian ancestry. There were 37 households out of which 24.3% had children under the age of 18 living with them, 62.2% were married couples living together, 2.7% had a female householder with no husband present, and 32.4% were non-families. 32.4% of all households were made up of individuals and 16.2% had someone living alone who was 65 years of age or older. The average household size was 2.16 and the average family size was 2.68. In the city, the population was spread out with 20.0% under the age of 18, 6.3% from 18 to 24, 28.8% from 25 to 44, 16.3% from 45 to 64, and 28.8% who were 65 years of age or older. The median age was 43 years. For every 100 females, there were 110.5 males. For every 100 females age 18 and over, there were 93.9 males. The median income for a household in the city was $28,750, and the median income for a family was $48,750. Males had a median income of $36,250 versus $20,313 for females. The per capita income for the city was $14,384. There were 16.7% of families and 30.5% of the population living below the poverty line, including 80.0% of under eighteens and none of those over 64.
