An early proposed name for the county was Gate, but Richland was decided upon instead as a way to entice new settlers.

[citation needed] As of the 2010 census, there were 9,746 people, 4,167 households, and 2,698 families in the county.

In terms of ancestry, 37.8% were German, 23.1% were Norwegian, 13.0% were Irish, 8.7% were American, and 6.5% were English.

Although most of the surface land of the county is devoted to ranching, oil exploration and production became important elements of the county's economy beginning with the discovery in 2000 of Elm Coulee Oil Field, part of the Bakken formation.

[11] Richland County voters have been reliably Republican, opting only one time for the Democratic Party candidate in national elections since 1948 (as of 2020).