Their range goes places range maps don't show. I've seen 3 in north eastern Nebraska. One near the Elkhorn river and two further north along Verdigris River. Several people I know have also reported seeing them along the Virdigris or Niobrara rivers.
I also saw one north of Gordon (western Ne) along the SD border. Nearly hit that one with the car as it loped across the road.
Few years ago I stopped at NE Game and Parks to buy deer tags and fur license and pick up the variety of literature they put out each year. I asked the gal behind the counter if the Commission was aware of wolverine presence in the state. She gave me kind of a funny look for a couple seconds, then responded affirmative. I was surprised by her response. At that time they were still denying the presence of mountain lions.