I have been looking at the centennial trail in South Dakota and I am trying to gather up more info for a possible thru hike next spring. If anyone in here have any experience and info I would really appreciate it. Looks like they are a couple of Nat Geo Maps that cover it, would these be sufficient or should I try to find better ones? A guidebook is available by Cheryl Whetham and Jukka Hutinieme. Reviews of the book are a little questionable but will probably be better than nothing. Looks like water may be an issue, tentatively planning on last half of May/first half of June but I have the ability to move the dates around. Any idea if this will help the water situation? I assume the weather at this time could be anything from 15 degrees and snow to 110 degrees and heatstroke. Does anyone know of any shuttle services for this area and resupply options along the way?