[3] Gilmore City was platted in 1884, not long after the railroad had been built through that territory in 1882.

Gilmore was the superintendent of the Fort Dodge & Des Moines rail line and later became division superintendent after the road was leased by the Rock Island Railway Company.

He is buried in Woodland Cemetery, Des Moines, Iowa.

[9] According to the United States Census Bureau, the city has a total area of 1.25 square miles (3.24 km2), all land.

[10] It contains one neighborhood, Stein's Rockin R Mobile Home Park, Iowa, on the Pocahontas side of town.

[11] Gilmore City lies along the northeastern margin (rim) of Manson crater, an impact structure buried by glacial till and outwash.

[12] As of the census of 2020,[14] there were 487 people, 220 households, and 128 families residing in the city.

Hispanic or Latino persons of any race comprised 1.2% of the population.

As of the census[15] of 2010, there were 504 people, 239 households, and 136 families residing in the city.

38.5% of all households were made up of individuals, and 15.1% had someone living alone who was 65 years of age or older.

As of the census[16] of 2000, there were 556 people, 257 households, and 160 families residing in the city.

35.8% of all households were made up of individuals, and 20.2% had someone living alone who was 65 years of age or older.