Answer:
French Canada - Had long-lasting tensions with the rest of Canada
Central Mexico - Original location of the Aztec empire
West Coast - Contains one of the most important economical states in the United States
Western Canada - Split by the Rocky Mountains
Explanation:
French Canada has always had some "tensions" with the rest of Canada, not necessarily resulting in conflict but they are a different ethnic group with a different language and different culture.
Central Mexico was the original location of the Aztec Empire, which was an alliance between three city-states located in the Valley of Mexico
The West Coast contains one of the most important economical states in the US: this is California, one of the most populated and the state with the highest GDP
Western Canada is split by the Rocky Mountains, the mountain range crossing most of Western North America
