Chronology of South Dakota History
An extensive timeline of the history of the state; an excellent resource from the state historical society.

Flags of the World: South Dakota
Information, images, and available history of the current and past flags of the state.

Geography and Maps of South Dakota
A plethora of geographical information and online maps from the About Geography site.

History of South Dakota
A history of the state from a 1904 textbook.

Infoplease.com: South Dakota Overview
A fantastic short historical overview, contemporary data, and a map from Infoplease.com