How about dividing the parties into four provinces with a line going east-west just north of Saskatoon and south of Edmonton and a north-South line running through the middle of saskatchewan
Southeast could be Winnipeg, Northeast could be Nelson (after the river). Northwest could be Athabasca (after the lake or river) Southwest maybe Piedmont or something indicating the presence of the mountains. The Southwest (including otl calgary, lethbridge, medicine hat, swift current, sask.) Is the one i'my least sure of. Bow, Oldman, and Red Deer (afterrivers) seem too strange. Maybe Blackfoot?