[4] It was named for Richland County, Ohio, where many of the early settlers migrated from.

[3]: Origin of the name of the county According to the U.S. Census Bureau, the county has a total area of 362 square miles (940 km2), of which 360 square miles (930 km2) is land[5]: Population tab, Population Density sub-tab  and 1.9 square miles (4.9 km2) (0.5%) is water.

[7] As of the 2010 United States census, there were 16,233 people, 6,726 households, and 4,438 families residing in the county.

[5]: Population tab, Population Density sub-tab  In 2010, there were 7,513 housing units, compared to 7,364 in 2020,[5]: Housing tab, Occupied Units sub-tab  at an average density of 20.9 per square mile (8.1/km2).

[5]: for 2020—Race alone tab, all sub-tabs  Those of Hispanic or Latino origin made up 1.3% (1.7%, 2020) of the population.