Yes you should have at minimum 1.5 hours. If you ride after they start a 3 a day run you can catch the first run in the morning and return on the last run. However you will have to make reservation to do that.
2021 Update: There is only a 15 minute layover if you choose the basic round trip. You can choose a longer layover of about 2-1/2 hours by choosing a later return train. Please call our reservation line at 605-574-2222 to discuss additional extended layover options.
It was a quick turnaround for us but we did get to visit the candy store next to the station.
I went on it years ago with a friend and we didn't have much time in key stone but enough to roam around, do some site seeing and run into a few little shops. It's a BLAST!!!
You could start in Keystone and do round trip to Hill City, if you wish to see more of sites in Keystone.
Very brief time spent in town
There is about half an hour max. So not really.
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