Walthill was platted in 1906 when the Chicago, Burlington and Quincy Railroad was extended to that point. It was named for Walter "Walt" Hill, son of railroad executive James J. Hill.
At the 2010 census, there were 780 people, 207 households and 158 families residing in the village. The population density was. There were 240 housing units at an average density of. The racial makeup of the village was 15.6% White, 0.6% African American, 80.9% Native American, 0.1% Asian, 0.3% Pacific Islander, 0.3% from other races, and 2.2% from two or more races. Hispanic or Latino of any race were 3.3% of the population. There were 207 households of which 55.1% had children under the age of 18 living with them, 38.2% were married couplesliving together, 26.1% had a female householder with no husband present, 12.1% had a male householder with no wife present, and 23.7% were non-families. 18.4% of all households were made up of individuals and 7.3% had someone living alone who was 65 years of age or older. The average household size was 3.77 and the average family size was 4.33. The median age was 24.8 years. 40% of residents were under the age of 18; 10.2% were between the ages of 18 and 24; 22% were from 25 to 44; 19.8% were from 45 to 64; and 8.2% were 65 years of age or older. The gender makeup was 49.9% male and 50.1% female.
At the 2000 census, there were 909 people, 284 households and 205 families residing in the village. The population density was 2,116.1 per square mile. There were 308 housing units at an average density of 717.0 per square mile. The racial makeup of the village was 27.61% White, 67.88% Native American, 0.11% Asian, 0.99% from other races, and 3.41% from two or more races. Hispanic or Latino of any race were 6.38% of the population. , Walthill, designated a National Historic Landmark in 1993 There were 284 households, of which 40.5% had children under the age of 18 living with them, 41.2% were married couples living together, 22.2% had a female householder with no husband present, and 27.5% were non-families. 25.4% of all households were made up of individuals and 12.7% had someone living alone who was 65 years of age or older. The average household size was 3.20 and the average family size was 3.80. 41.3% of the population were under the age of 18, 7.6% from 18 to 24, 25.0% from 25 to 44, 14.9% from 45 to 64, and 11.3% who were 65 years of age or older. The median age was 27 years. For every 100 females, there were 95.5 males. For every 100 females age 18 and over, there were 92.1 males. The median household income was $28,750 and the median family income was $29,500. Males had a median income of $26,719 and females $21,500. The per capita income was $10,051. About 18.2% of families and 23.0% of the population were below the poverty line, including 26.1% of those under age 18 and 16.5% of those age 65 or over.
