The "Kansas solidiers suffered the highest mortality rate" claim is all over the web, including the official State of Kansas web site. I suspect the source of that claim is the "Deaths in Action and From Wounds" table in the Adjutant General's Report. It seems that it may be a claim that is not backed up by the facts.

I agree that report has questionable data. I thought it was strange they would include desertions and dishonorable discharges in casualties. Also, there doesn't seem to be any supporting math for the 20,097 number by unit (although there is a break-down by year).