Now I can say that I've been to Wall Drug. As if the signs along I-90 weren't entertainment enough, the store includes some entertaining historic photos, articles, letters, and even a T-Rex that comes to life occasionally (visit this site to see it in action: http://www.walldrug.com/family_fun )
I was disappointed to find the exit De Smet closed as this is the location of quite a lot of Laura Ingalls Wilder history. Oh well, maybe the T-Rex was enough for one day. ;-) I arrived in Sioux Falls just in time as it started raining about 10 minutes after I checked in to my hotel.
The rain has stopped and I'm going to clean up before venturing out to find a good spot to have dinner.