The county was created on July 3, 1959, in anticipation of the termination of the Menominee Indian Reservation in 1961. The reservation status was restored in 1973, and is now co-extensive with the county. Most of the land within the county boundary is under Federal Trust for the exclusive use by enrolled Menominee Indians. Scattered parcels that were purchased during Termination, as well as many lots around the Legend Lake area in the southeastern part of the county, are the only parts of the county that are privately-owned by non-Indians.
Most of Menominee County's population consists of Menominees.
At the 2000 census, there were 4,562 people, 1,345 households and 1,065 families residing in the county. This total makes it the least-populated county in the state. The population density was 13 per square mile (5/km²). There were 2,098 housing units at an average density of 6 per square mile (2/km²). The racial makeup of the county was 11.57% White, 0.07% Black or African American, 87.26% Native American, 0.02% Pacific Islander, 0.33% from other races, and 0.75% from two or more races. 2.67% of the population were Hispanic or Latino of any race. 5.0% were of German ancestry according to Census 2000. 89.8% spoke English, 7.0% Menominee and 1.6% Hmong as their first language.
There were 1,345 households of which 42.20% had children under the age of 18 living with them, 42.50% were married couples living together, 26.60% had a female householder with no husband present, and 20.80% were non-families. 16.50% of all households were made up of individuals and 6.40% had someone living alone who was 65 years of age or older. The average household size was 3.35 and the average family size was 3.66.
Age distribution was 38.90% under the age of 18, 8.40% from 18 to 24, 24.70% from 25 to 44, 19.50% from 45 to 64, and 8.50% who were 65 years of age or older. The median age was 28 years. For every 100 females there were 97.30 males. For every 100 females age 18 and over, there were 92.30 males.