I think you'll like these maps, they don't have a North and South Dakota. Just Dakota

made in 1883, and it is BIG, so click on these for full size. All of the shaded area near the railroad? Given to the railroad to profit from in order to get the railroad to build a means of transportation the US Govt could then use to move military and supplies

1882

this last one is 1887, and if you click on the last link below, you can get a really magnified look at it's details

https://tile.loc.gov/image-services/iiif/service:gmd:gmd370:g3701:g3701p:rr005010/full/pct:25/0/default.jpg
https://www.loc.gov/item/98688748/
https://www.loc.gov/item/98688749/
https://www.davidrumsey.com/luna/servlet/detail/RUMSEY~8~1~24214~880043:Map-N-P-R-R-