I did not make this map, but it is a Q-Bam and may aid your efforts.....So right now I'm working at really defining alternate borders of the US. I'm stuck around the Colorado River and California as a whole. To do what I'm trying, I would need the ridges, rivers, and even older counties to be accurately mapped. However, most sources I have found are not even close to the projections we use on AH - and this BAM specifically. I'm not stating this for anybody to do it for me, but rather to ask for advice on how to accurately do it on my own. The Colorado on these maps looks so wrong but as far as I know it isn't. Which throws off how I think borders would look on a base map like this.
And that make me think translating a map like this would be an absolute nightmare even though it seems close enough. Where would I even begin?