The German Prince Maximilian of Weid, according to this Bismarck Tribune article, was an explorer akin to (and slightly later than) Lewis and Clark.  He also traveled through the North Dakota area and made his own discoveries.

From the article:

He acquired an unparalleled collection of Mandan and Hidasta goods. And he kept detailed illustrated journals that would in sheer historical detail put the earlier, more famous explorers’ notes to shame.

Now the Lewis and Clark Interpretive Center in Washburn is featuring Prince Maximilian and the work of the gifted artist Karl Bodmer, who accompanied him, as a way to celebrate the 175th year since their journey.