The county was organized July 3, 1871, and was named for Wilmot Wood Brookings (1830-1905), a politician and pioneer of southeastern South Dakota.

Medary was the first county seat, from 1871 to 1879, when it was moved to the city of Brookings.

Brookings County is on the east side of South Dakota.

[4] The county terrain consists of sloped flatlands, marked by numerous lakes and ponds especially in the western part.

In terms of ancestry, 47.9% were German, 24.3% were Norwegian, 11.9% were Irish, 6.9% were English, 6.1% were Dutch, and 2.0% were American.

In only two national elections since 1932 has the county selected the Democratic Party candidate.