Added 2021-07-14
This unique park doesn't get enough credit! You can get some great views from the car, but a short hike or two make your time especially worthwhile. Twin Sisters hike is a short .4 miles with great photo opp potential (be careful to respect the environment), and the Cap Rock loop is .5 miles with a badlands feel to it.
Eyefull Vista is another can't-miss easy stop.
Link to park map: https://fwp.mt.gov/binaries/content/assets/fwp/pdfs/stateparks/parkmaps/makoshika-trail-and-campground-map.pdf
This park gets especially hot and dry, so be sure to pack enough water along.
Glendive Dinosaur & Fossil Museum is also located nearby if dinosaurs are your jam.