[2] Its northern boundary is the Canada–United States border south of Saskatchewan.

It was named for American Civil War General Philip Sheridan.

[citation needed] As of the 2010 census, there were 3,384 people, 1,587 households, and 944 families living in the county.

In terms of ancestry, 33.8% were Norwegian, 26.0% were German, 12.0% were Danish, 11.6% were Irish, 5.5% were Swedish, 5.3% were English, and 5.0% were American.

Sheridan County had a strong Communist Party presence in the first half of the 20th century.

Foster received 18% of the vote in the county, his strongest performance nationwide.