When entering a roundabout, you must yield the right-of-way to

Pedestrians and vehicles that are already in an intersection have the right-of-way. And a roundabout is a circular intersection. When entering a roundabout, you must yield the right-of-way to pedestrians and vehicles already in the circle. Note: At the time of this writing, South Dakota doesn't have any roundabouts, but the South Dakota Department of Transportation is planning several. ["Roundabouts," South Dakota Department of Transportation, http://www.sddot.com/transportation/highways/planning/roundabout/Default.aspx]