In 1827, a 'Round Prairie Post Office' was opened near the southern border of a much larger historic Round Prairie Township. In 1836, a historic town of 'Bloomfield', next to or containing the Round Prairie Post Office, was surveyed.. In 1841 the Round Prairie Post Office was shut down and moved about 1/2 mile southward, clearly into Cedar Township, and was renamed 'New Bloomfield Post Office', around which today's town of New Bloomfield formed. Details of relevant township boundary changes are given in the article on Round Prairie Township.
As of the census of 2010, there were 669 people, 256 households, and 173 families living in the city. The population density was. There were 283 housing units at an average density of. The racial makeup of the city was 94.2% White, 1.0% African American, 0.9% Native American, 0.6% Asian, 0.7% from other races, and 2.5% from two or more races. Hispanic or Latino of any race were 1.2% of the population. There were 256 households of which 37.9% had children under the age of 18 living with them, 52.0% were married couplesliving together, 12.5% had a female householder with no husband present, 3.1% had a male householder with no wife present, and 32.4% were non-families. 26.2% of all households were made up of individuals and 9.8% had someone living alone who was 65 years of age or older. The average household size was 2.61 and the average family size was 3.15. The median age in the city was 34.2 years. 27.4% of residents were under the age of 18; 8.3% were between the ages of 18 and 24; 30.5% were from 25 to 44; 24.5% were from 45 to 64; and 9.3% were 65 years of age or older. The gender makeup of the city was 49.0% male and 51.0% female.
2000 census
As of the census in 2000, there were 599 people, 237 households, and 158 families living in the city. The population density was 1,261.3 people per square mile. There were 253 housing units at an average density of 532.8 per square mile. The racial makeup of the city was 96.49% White, 0.50% African American, 0.83% Native American, 0.33% Asian, and 1.84% from two or more races. Hispanic or Latino of any race were 0.83% of the population. There were 237 households out of which 41.4% had children under the age of 18 living with them, 50.6% were married couples living together, 15.2% had a female householder with no husband present, and 33.3% were non-families. 31.2% of all households were made up of individuals and 16.0% had someone living alone who was 65 years of age or older. The average household size was 2.53 and the average family size was 3.20. In the city the population was spread out with 30.7% under the age of 18, 6.2% from 18 to 24, 34.6% from 25 to 44, 17.0% from 45 to 64, and 11.5% who were 65 years of age or older. The median age was 33 years. For every 100 females, there were 78.3 males. For every 100 females age 18 and over, there were 79.7 males. The median income for a household in the city was $32,969, and the median income for a family was $41,023. Males had a median income of $25,556 versus $23,125 for females. The per capita income for the city was $15,180. About 6.5% of families and 9.1% of the population were below the poverty line, including 13.1% of those under age 18 and 13.0% of those age 65 or over.
