The first settlement was made in the Oak area in the 1860s. Oak was platted on its current site in 1888 when the Fremont, Elkhorn & Missouri Valley Railroad was extended to that point. It was named from nearby Oak Creek.
As of the census of 2010, there were 66 people, 30 households, and 15 families living in the village. The population density was. There were 38 housing units at an average density of. The racial makeup of the village was 98.5% White and 1.5% from two or more races. Hispanic or Latino of any race were 1.5% of the population. There were 30 households of which 33.3% had children under the age of 18 living with them, 46.7% were married couplesliving together, 3.3% had a female householder with no husband present, and 50.0% were non-families. 40.0% of all households were made up of individuals and 3.3% had someone living alone who was 65 years of age or older. The average household size was 2.20 and the average family size was 3.07. The median age in the village was 33.5 years. 25.8% of residents were under the age of 18; 7.6% were between the ages of 18 and 24; 33.4% were from 25 to 44; 25.8% were from 45 to 64; and 7.6% were 65 years of age or older. The gender makeup of the village was 54.5% male and 45.5% female.
2000 census
As of the census of 2000, there were 60 people, 31 households, and 15 families living in the village. The population density was 405.1 people per square mile. There were 36 housing units at an average density of 243.1 per square mile. The racial makeup of the village was 100.00% White. There were 31 households out of which 25.8% had children under the age of 18 living with them, 38.7% were married couples living together, and 48.4% were non-families. 41.9% of all households were made up of individuals and 25.8% had someone living alone who was 65 years of age or older. The average household size was 1.94 and the average family size was 2.63. In the village, the population was spread out with 20.0% under the age of 18, 13.3% from 18 to 24, 16.7% from 25 to 44, 18.3% from 45 to 64, and 31.7% who were 65 years of age or older. The median age was 46 years. For every 100 females, there were 114.3 males. For every 100 females age 18 and over, there were 118.2 males. As of 2000 the median income for a household in the village was $21,875, and the median income for a family was $27,500. Males had a median income of $19,688 versus $12,500 for females. The per capita income for the village was $11,460. There were 5.0% of families and 17.5% of the population living below the poverty line, including 46.2% of under eighteens and 19.0% of those over 64.
