2020 census As of the
2020 census, Monument had a population of 115. The median age was 48.8 years. 16.5% of residents were under the age of 18 and 28.7% of residents were 65 years of age or older. For every 100 females there were 113.0 males, and for every 100 females age 18 and over there were 128.6 males age 18 and over. 0% of residents lived in urban areas, while 100.0% lived in rural areas. There were 67 households in Monument, of which 38.8% had children under the age of 18 living in them. Of all households, 31.3% were married-couple households, 32.8% were households with a male householder and no spouse or partner present, and 25.4% were households with a female householder and no spouse or partner present. About 38.8% of all households were made up of individuals and 20.9% had someone living alone who was 65 years of age or older. There were 55 households, of which 29.1% had children under the age of 18 living with them, 43.6% were
married couples living together, 9.1% had a female householder with no husband present, 3.6% had a male householder with no wife present, and 43.6% were non-families. 38.2% 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 2.33 and the average family size was 3.23. The median age in the city was 40.5 years. 24.2% of residents were under the age of 18; 5.6% were between the ages of 18 and 24; 26.6% were from 25 to 44; 27.4% were from 45 to 64; and 16.4% were 65 years of age or older. The gender makeup of the city was 54.7% male and 45.3% female.
2000 census As of the census of 2000, there were 151 people, 68 households, and 41 families residing in the city. The population density was . There were 81 housing units at an average density of . The racial makeup of the city was 95.36% White, 3.97% Native American, and 0.66% from two or more races. There were 68 households, out of which 26.5% had children under the age of 18 living with them, 47.1% were married couples living together, 7.4% had a female householder with no husband present, and 39.7% were non-families. 32.4% of all households were made up of individuals, and 11.8% had someone living alone who was 65 years of age or older. The average household size was 2.22 and the average family size was 2.78. In the city, the population was spread out, with 25.2% under the age of 18, 7.3% from 18 to 24, 27.2% from 25 to 44, 23.8% from 45 to 64, and 16.6% who were 65 years of age or older. The median age was 35 years. For every 100 females, there were 118.8 males. For every 100 females age 18 and over, there were 113.2 males. The median income for a household in the city was $24,000, and the median income for a family was $45,714. Males had a median income of $38,750 versus $21,250 for females. The
per capita income for the city was $15,814. There were 6.8% of families and 17.1% of the population living below the
poverty line, including 19.2% of under eighteens and 8.0% of those over 64. ==Transportation==