Barnes City came about as a result of the Chicago, Rock Island, and Pacific Railroad needing a central link between Montezuma[4][circular reference] and Thornburg.

[5] According to the United States Census Bureau, the city has a total area of 0.59 square miles (1.53 km2), all land.

[6] As of the census of 2020,[8] there were 156 people, 80 households, and 47 families residing in the city.

The racial makeup of the city was 99.4% White and 0.6% Native American.

40.9% of all households were made up of individuals, and 13.6% had someone living alone who was 65 years of age or older.

As of the census[10] of 2000, there were 201 people, 92 households, and 50 families living in the city.

The racial makeup of the city was 99.50% White and 0.50% African American.

37.0% of all households were made up of individuals, and 20.7% had someone living alone who was 65 years of age or older.

About 14.0% of families and 20.7% of the population were below the poverty line, including 43.5% of those under the age of eighteen and 5.9% of those 65 or over.