The Prairie Wind Casino (12 miles east of Oelrichs on U.S. 18, 605/867-6300 or 800/705-9463, www.prairiewindcasino.com [1], year-round 24 hours daily) started as a couple of double-wide trailers, graduated to a tent-like building, and in 2007 opened its current complex of buildings, which includes the casino, a hotel, and a restaurant.
Blackjack, poker, and video and real slot machines are the order of the day. Tournaments are held on a regular basis. Call the casino for information about the schedule. No alcohol is served on reservation land.
For a day trip to the casino, there are several buses available. From Hot Springs [2], buses travel to the casino on the first and third Tuesday of every month. Call 605/745-5765 for information.
From Whitewood, Sturgis, and Rapid City [3], buses travel to the casino on the second and fourth Thursday of every month. Call 605/717-9737 for information.
Also from Rapid City, a bus travels to the casino every Sunday. Call 605/393-0258 for information.
Links:
[1] http://www.prairiewindcasino.com
[2] http://www.moon.com/destinations/mt-rushmore-the-black-hills/the-southern-hills/hot-springs
[3] http://www.moon.com/destinations/mt-rushmore-the-black-hills/mount-rushmore-and-the-central-hills/rapid-city