The Mt. Rushmore area of the Needles is mostly granite sport. There are a few climbs that require a bit of gear. Most of the Rushmore area is rap bolted and thus less committing than the Sylan Lake area. Sylan can be quite butt-puckering, depending on the route.
There is also a lot of granite bouldering in the area which is good. There is some good limestone in Spearfish Canyon and Victoria Canyon as well, also sport bolted.
My personal favorite sport areas around the Black Hills are the Chopping Block/Monster/Middle Marker areas on the granite and Victoria Canyon (the VC) with its excellent limestone.
there isn't a regional forum for either Dakota, but there is a state page for SD, and plenty of info on the needles area, see?
The whole 'North Dakota = South Dakota = the rockies' thing came up here just recently. I do think it's fair to say that there is no outdoor rock climbing in North Dakota, but I'd love to have someone prove me wrong.
Rushmore is closely bolted sport climbing for the most part. In the Needles proper, routes tend to be more run out though there are a handful of sport routes behind Sylvan Lake and especially on Moonlight Ridge.