The Souris River is flooding Minot, North Dakota. On the CBC news a Minot resident blames Saskatchewan for this, 'they should have done something'. The Souris eventually joins the Assiniboine, after it crosses the border again, back into Manitoba. The Assiniboine flooded earlier this spring and will perhaps flood again. Winnipeg also keeps its eye on Fargo, North Dakota, on the Red River. The Assiniboine joins the Red in downtown Winnipeg. In the 1996 Red River flood Winnipegers blamed Fargo for not better controlling the river flow.
The 49th parallel is an abstract political division that serenely ignores topography: global mathematics trumps geophysical realities. Before the US Survey, before the Dominion Grid, before enlightened Europeans started to delineate territory in this seemingly empty-ish land, there were aboriginal territories: precise, negotiated at their borders by treaty, surveyed orally in a metes and bounds system.
Sliammon First Nation territory clearly is topographically based: it controls the watershed on the western slopes of the Coast range, the waterway and fishing beds of the inland passage and the opposite beach, securing the whole width of the strait. Fresh water systems, food, sea borne transportation capacity, security: these are the things that boundaries delineate.
This 1891 map of watersheds in what was called the arid regions of the western United States shows a division of land that could have been a series of small states, with control over their own water resources and all the potential agricultural and animal resources a watershed contains.
Or, looking at a map of pre-contact cultural zones in North America, one can see how there is a huge territory that controls the Great Lakes. Another has the whole western watershed of the Mississipi, another group the eastern side. The Great Divide separates the peoples of the watersheds that go to the Pacific from those of the plains: the north to Hudson's Bay, south to the Gulf of Mexico. The boreal forest is one huge cultural group, as is the high Arctic.
Topological environmental divisions as political territories: what a novel idea. One could only blame oneself for mismanaging one's resources.