[2] The county is named for United States President Warren G. Harding, and was created (from parts of Union and Mora Counties) on the day of his inauguration as president on March 4, 1921, making him the most recent president to have a county in any state named after him.

[3] The only incorporated cities in Harding County are Roy and Mosquero.

[4] It is divided between a high, nearly treeless prairie to the northwest (the southern limit of the High Plains), and a lower semi-desert rangeland to the southeast, by the eastern portion of the steep Canadian Escarpment.

The Canadian River, in a deep and narrow canyon, forms the western border with Mora County; the southwest border runs along the edge of the Bell Ranch land in San Miguel County.

The eastern part of Harding County is underlain in part by the Bravo Dome carbon dioxide gas field, which is commercially extracted.

As of the 2000 census,[10] there were 810 people, 371 households, and 231 families living in the county.

35.30% of all households were made up of individuals, and 21.00% had someone living alone who was 65 years of age or older.

As of the 2010 census, there were 695 people, 349 households, and 213 families living in the county.