[3] On June 4, 1891, the county's area was increased by the addition of Farm Island, in the Missouri River downstream of Pierre.

[4] Hughes County is part of the Pierre, SD Micropolitan Statistical Area.

The Missouri River forms the southwestern boundary line of Hughes County.

[5] The county terrain generally slopes to the southeast, although the hills along the west fall off into the river valley.

The county's highest point is on the upper part of the east boundary line, at 1,952 ft (595 m) ASL.

[7] Pierre Regional Airport (PIR) serves Hughes County and the surrounding communities.

In the State House Hughes is part of district 24, which is held by Republicans Tad Perry and Mark Venner.