I'm reading The Company right now by Stephen Brown. Someone on one of these threads recommended it a while ago. It's about the Hudson Bay Company and it's really interesting to see how exploration of the interior of the continent took place, how trade networks operated and changed, and how indigenous culture adapted to the changing economic situation. I think if you're at all curious about Canadian or Western US history then this is a great read.

I think Brown is a pretty good writer and the book is very engaging. He raises some good comparisons with modern society and asks some interesting questions about how cultures interact.