The Canadian federal government denies the provinces sole possession of their own mineral resources.
I don't know if this is true. Having lived in western Canada and done business up there, I can only remember dealing with industries like logging and oil/gas that dealt with the provincial governments. One of the great advantages of NAFTA, in fact, is that it prohibits the Canadian government from getting too heavily involved in any of their industries up there.
As you correctly point out, the natural trend over time has been for Canadian provinces and regions to trade more freely with their southern counterparts than their Canadian neighbors. I don't see that changing anytime soon, unless it's the U.S. (not Canada) that pushes to change it.
As to mineral rights, it looks like the central government is just now moving that way.
OTTAWA, Feb. 10, 2017 /CNW/ - Ensuring our provincial and territorial partners are treated fairly is fundamental to creating jobs and economic prosperity for middle-class Canadians.
Canada’s Minister of Natural Resources, the Honourable Jim Carr, and Manitoba’s Minister of Growth Enterprise and Trade, the Honourable Cliff Cullen, today formally announced an agreement to transfer the Federal Soldier Settlement Board mineral rights and associated revenues from the Government of Canada to the Government of Manitoba. This agreement provides Manitoba with a payment of about $13 million for revenues generated from past oil and gas activities on these lands.
The Soldier Settlement Board was created by the Government of Canada in 1917 to assist veterans returning from the First World War to set up farms. Lands in various provinces were leased to veterans, but the federal government reserved the mineral rights beneath the land surface.