A post office called Plummer has been in operation since 1903. The city was named for Charles A. Plummer, who established two mills near the original town site.
As of the census of 2010, there were 292 people, 128 households, and 68 families residing in the city. The population density was. There were 141 housing units at an average density of. The racial makeup of the city was 96.2% White, 1.7% Native American, and 2.1% from two or more races. Hispanic or Latino of any race were 3.1% of the population. There were 128 households of which 30.5% had children under the age of 18 living with them, 43.8% were married couplesliving together, 7.8% had a female householder with no husband present, 1.6% had a male householder with no wife present, and 46.9% were non-families. 39.8% of all households were made up of individuals and 11% had someone living alone who was 65 years of age or older. The average household size was 2.28 and the average family size was 3.18. The median age in the city was 35 years. 28.4% of residents were under the age of 18; 4% were between the ages of 18 and 24; 31.6% were from 25 to 44; 24.7% were from 45 to 64; and 11.3% were 65 years of age or older. The gender makeup of the city was 51.7% male and 48.3% female.
At the 2000 census, there were 270 people, 125 households and 71 families in the city. The population density was 95.3 per square mile. There were 130 housing units at an average density of 45.9 per square mile. The racial makeup of the city was 98.89% White, 0.74% African American and 0.37% Native American. There were 125 households of which 23.2% had children under the age of 18 living with them, 48.0% were married couples living together, 7.2% had a female householder with no husband present, and 42.4% were non-families. 37.6% of all households were made up of individuals and 23.2% 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 2.89. The age distribution was 22.6% under the age of 18, 8.1% from 18 to 24, 24.4% from 25 to 44, 21.9% from 45 to 64, and 23.0% who were 65 years of age or older. The median age was 42 years. For every 100 females, there were 88.8 males. For every 100 females age 18 and over, there were 90.0 males. The median household income was $29,286, and the median family income was $43,438. Males had a median income of $27,500 versus $23,906 for females. The per capita income for the city was $17,506. About 1.6% of families and 8.5% of the population were below the poverty line, including none of those under the age of eighteen and 17.6% of those sixty five or over.
