[3] The river, in turn, was named for the yellow sandstone cliffs in what is now Yellowstone County.[4] Yellowstone County is included in the Billings, Montana Metropolitan Statistical Area.[citation needed] As of the 2010 census, there were 147,972 people, 60,672 households, and 38,367 families residing in the county.In terms of ancestry, 32.4% were German, 14.0% were Irish, 11.3% were English, 10.0% were American, and 9.9% were Norwegian.Lyndon B. Johnson's 1964 landslide was the last time that the county voted for a Democratic candidate.