Partly, yes. I spent a fair amount of time looking up names of various UP cities and towns, trying to figure out the history and the languages they came from and so on. Copper River made sense as the name of a town connected to the mining industry. I based it very loosely on the town of Negaunee.

Tamarack ... I looked up a lot of non-English town names, both names lifted directly from other languages and corruptions of non-English words. I don't remember exactly where Tamarack came from, but I really liked the sound of it. (This was at least the third name I tried for that town.)