Rough Rider State Park sits just outside Medora in the North Dakota Badlands. It is a simple, outdoorsy stop, with primitive camping and access to riding, walking, and canoeing rather than polished visitor-centre attractions.
The park makes most sense if you are already using Medora as a base for Theodore Roosevelt National Park and want a quieter place to stretch out. Expect basic facilities and check current access before building a day around it.