I have personnally found that most NPS rangers and guides are not well educated in the history of the Parks they serve. Especially of a detailed history. I find that most are not stationed at a single location more than 3 or 4 years before they are transferred either by request or otherwise, turned over. The second reason is political correctness policies and NPS agendas. For example the directive a few years back by the National Parks Service that directed National Military Parks were to say that the War between the States was only about Slavery.

I do not trust anything that a Park Range or Guide tells me about the history of a location, nor very much of the signage, because I don't trust the motivations of the Nation Parks Service and the National Military Parks.