Oregon boundary dispute - ATL Seattle, Canada

[Agent_J]

What if there was an earlier solution of the Oregon boundary dispute?

In 1818, in a last-ditch effort to avoid joint occupation, Gallatin and Rush offered the British the Gulf of Georgia and the territory that it drained. This would have awarded "all the territory draining west from the Cascade divide and north from the Columbia River divide into the gulf" and the entirety of the Puget Sound along with the Straits of Georgia and Juan de Fuca to the United Kingdom.[1]

This offer, unofficial and confidential, was evidently rejected by the British out of hand; it was not mentioned by the British plenipotentiaries in their report submitted to the Foreign Office. Neither side regarded the harbors in the Gulf of Georgia is being of very great importance compared to the question of who would control the valley of the Columbia south of the 49th parallel.

As Merk notes, "Ultimately some of these harbors did become major ports. They developed into entrepots of a world-wide commerce. They became so largely because railroads gave them overland connection with a continental interior. But in 1818 railroads were a development still in the future. No one dreamed of the impact they would make on modern life."[2]

POD: British accept Gallatin-Rush offer in 1818. What impact would that have had on Canada and the USA?
(Seattle, Tacoma, Olympia, etc. would be part of Canada)


[1]Merk, Frederick (1950), "The Ghost River Caledonia in the Oregon Negotiation of 1818", The American Historical Review, 50 (3): 530–551
[2]Frederick Merk's *The Oregon Question: Essays in Anglo-American Diplomacy and Politics* (Cambridge, MA: Harvard UP 1967). pp. 59-60.

Edit: Updated [1] re borders

 

[JackLumber]

Not much as far as I know, im under the impression that Vancouver is a superior port so it will reach the same prominence as OTL and America will just have different Ports for it's trade.

 

[Agent_J]

Would BC still join the Confederation? Could Cascadia happen?

And let's say BC stills joins Confederation, could there be a Golden Horseshoe for southern BC? What impact would that have on Canada?

 

[Agent_J]

bumping for afternoon

 

[Shevek23]

The first consequence of course is defusing a potential conflict that OTL festered for a couple decades more. With clear boundaries US administrations, even especially expansionistic ones, should be deterred from revisiting this issue--conceivably there might be conflicts over inland borders but these ought to be well taken care of when settling the coastal issues.

Conceivably conflict might resume anyway--OTL a great many settlers in the region, some of US origin, others born British subjects, had some issues with the policies of both British colonial government and the interlocked Hudson Bay Company. The Company in particular wished to limit settlement on the mainland in favor of keeping good relations with Native peoples. I do think that over time, even if HBC remains powerful and discouraging of settlement, it will occur anyway, but the more frustrated large numbers of locals are the more agitation among them for the option of seceding from British control and joining the USA. Secession with the intention of remaining independent seems unlikely to gain strong support since they'd need protection from an irritated Britain. Conceivably then by a two-step, the USA could wind up controlling much or all of OTL BC!

However I think even very aggressive US administrations would be very cautious about going to war over Britain; only if it were linked to much larger issues, such as the fate of eastern BNA, or to a conflict over some other issue, such as Britain seeking to dissuade a US attack on Mexico, or intervening adversely in the Civil War, would US Presidents consider risking such an obviously punishing war. The question of whether the US would win or lose such a war is clearly not much settled by the situation in the Pacific Northwest!

Assuming the USA manages to remain rational and avoid conflict with Britain, we can anticipate relations steadily improving as OTL.

The Puget Sound ports are clearly something the USA as a whole would have some regrets about not controlling, but with good relations with Britain and/or a subsequent Dominion government, whether part of Canada or separate from it, US railroad networks and other transport grids seem likely to more or less integrate into the region so US regions better served via the bay would have opportunities to develop more or less as OTL.

Portland Oregon, with Oregon state presumably extending into some OTL Washington territory presumably to the watershed, so the Columbia mouth is completely under US control, would benefit relative to OTL as our northernmost port on the Pacific, therefore favored for Naval bases, and would presumably accumulate other military assets OTL in Washington State. Portland would also be somewhat favored commercially though the superiority of the Sound ports would perhaps limit this.

The loss of the territory of Washington State to Britain probably will not drastically affect the USA.

Expanding BC southward like that would of course be a great asset to that province/Dominion, maybe enough to justify it remaining separate from Canada, but I suspect the logic of uniting Canada into one Dominion would probably still prevail, only now with BC being stronger within the Dominion, for whatever that is worth.

I do wonder how settling the matter in the 1820s would affect the election of Polk, assuming the whole US succession of Presidents is not butterflied (not unreasonable with the Northwest so remote). As I understand it (largely influenced by Devito's Year of Decision), US expansionism as reflected in his electoral popularity was as much concerned with possible acquisitions at British expense as incorporating Texas and further Mexican territory, and DeVoto suggests it was Polk's genius to defuse the British conflicts and divert national greed southwestward. Does this imply that with the Northwest, the flash point where US claims overlapping British would be most easy for American jingos to justify, removed decades in advance that Polk would simply not be elected? Or would his election still happen, and signal either fears of his menacing British claims (including in the NW) without pretext or a more ominous and obvious set of designs on Mexico?

The least change possible has Polk being clearly aiming at Mexico from the beginning, a less troubled US/British relationship that only accelerates the general trend toward cooperation, and general outcomes differing from OTL not very interestingly, except for people who live in Washington or BC of course.

Such an early and greater concession toward maximal British claims might also impede US acquisition of Alaska, but then again the Russians had reasons not to want to offer it to Britain, and also to seek to unload it with some profit, and the USA would, barring significant butterflies as of the late 1860s, still be first in line from the point of view of Russian interest--we had an obvious stake in acquiring it (relative to other powers excepting Britain, with Japan essentially not on the map of imperial powers yet, even if this stake was not apparent to US critics of "Seward's Folly," nor is Britain in a much stronger position to oppose it (barring the possible butterfly of their perhaps having conquered it earlier) nor have any stronger motives than OTL to stand in the way. With Alaskan territory being even farther from the nearest contiguous US territory than OTL, if anything British objections might be milder, since if push came to shove we'd have a harder time defending it from British hostility, while they would be stronger in the Pacific NW while we would be more vulnerable, what with Oregon being potentially threatened both by land and by sea, and with nothing backing it up except perhaps Californian ports far to the south. So I'd think the Alaska purchase is likely to go forward as well.

 

[Galba Otho Vitelius]

Checking a map, it looks like the northern boundary of the US would proceed westward on its current straight line from Lake of the Woods until it hit the Cascades watershed, then follow the Cascade watershed to Mt. Rainier (which would be in Canada), then another straight line west to the Pacific.

If my memory from the "Underground Seattle" tour (well worth doing) is correct, Seattle's big break was as the southern terminus of the boat to the Alaskan goldfields. Does this still happen if the city is not within the United States? My guess is that the boats leave from Portland and Seattle remains dependent on the timber industry. And Boeing either is not located there or does not receive US defense contracts if it is, so the whole Puget sound area remains rural and much less populated than IOTL.

Vancouver on the other hand is bigger and Portland is much bigger, with pretty much all the military installations and military related industries that are around Seattle IOTL located there. Most of the famous people associated with Seattle come from Portland instead. The Seahawks and the Mariners both play in Portland, though under different names. American TV shows and movies set in Seattle are set in Portland instead. Pretty much Portland ITTL becomes Seattle. Eugene might develop as TTL Portland.

IOTL, the Puget Sound area now has just under 5 million people. ITTL, it has under 2 million people, with 2.5 to 3 million more living in the Portland metropolitan area (including IOTL southwestern Washington) than IOTL and a few hundred thousand more in Vancouver.

Washington is not split from Oregon. Puget Sound is part of British Columbia (again its much more rural), with southwestern Washington in Oregon and Eastern Washington attached to either Oregon or Idaho. There is no state capital in Olympia. British Columbia gets another two dozen more MPs, nearly all of these going to the Conservatives since ITTL BC is more consistently Conservative. All but a couple members of Washington's House of Representatives delegation go to Oregon, with Idaho picking up one or two extra Congressmen if it gets Eastern Washington, and, since the population of the US is lower by a couple million, whichever state just misses picking up another Congressman in any particular Census gets that Congressman. In 2010, the first bubble state was North Carolina, which would have gained a fourteenth Congressman, then Missouri, which might have kept its ninth Congressman. The political complexion of neither Oregon nor Idaho winds up changing that much.

States tend to be admitted to the union in pairs. Looking up the dates of admission to states to the union, the only clear exceptions to this rule that I found were Vermont, after which there has almost always been an even number of states, Ohio, Louisiana, New Mexico, and Oklahoma. Washington was admitted in 1888-9 as part of a block of six states, the others being North Dakota, South Dakota, Wyoming, Montana, and Idaho. The Republican Congress of that time was not doing some gerrymandering with state admissions, the effects of which are still with us today, which is why there are two Dakotas and Wyoming is not part of Montana. They might have admitted an oddly-shaped, under populated Washington anyway. They might have also moved up the admission of New Mexico. My guess is that Idaho would have been split, with IOTL eastern Washington and northern Idaho forming a state, and the southern two thirds of Idaho becoming Idaho. What is now southwestern Washington would have remained with Oregon. The eastern Washington/ northern Idaho state would still have a larger population than either Dakota, Montana, Wyoming, or Idaho. It probably would have been called "Washington" but I have no idea where the state capital would be (no, not Spokane, state capitols are almost never in the state's largest city).

Olympic National Park and Mt. Rainier are part of the Canadian national parks system.

 

[The Gunslinger]

If the Americans don't have a port in Puget Sound there isn't really a point in fighting with Britain over the Columbia River as a border. That was a huge portion of the dispute.

 

[Agent_J]

Thank you for the replies everyone. I admit I'm not great at coming up with this stuff, but it's a burning question in my mind, so I really enjoy reading everyone's theories! Keep em coming

 

[JackLumber]

Checking a map, it looks like the northern boundary of the US would proceed westward on its current straight line from Lake of the Woods until it hit the Cascades watershed, then follow the Cascade watershed to Mt. Rainier (which would be in Canada), then another straight line west to the Pacific.

If my memory from the "Underground Seattle" tour (well worth doing) is correct, Seattle's big break was as the southern terminus of the boat to the Alaskan goldfields. Does this still happen if the city is not within the United States? My guess is that the boats leave from Portland and Seattle remains dependent on the timber industry. And Boeing either is not located there or does not receive US defense contracts if it is, so the whole Puget sound area remains rural and much less populated than IOTL.

Vancouver on the other hand is bigger and Portland is much bigger, with pretty much all the military installations and military related industries that are around Seattle IOTL located there. Most of the famous people associated with Seattle come from Portland instead. The Seahawks and the Mariners both play in Portland, though under different names. American TV shows and movies set in Seattle are set in Portland instead. Pretty much Portland ITTL becomes Seattle. Eugene might develop as TTL Portland.

IOTL, the Puget Sound area now has just under 5 million people. ITTL, it has under 2 million people, with 2.5 to 3 million more living in the Portland metropolitan area (including IOTL southwestern Washington) than IOTL and a few hundred thousand more in Vancouver.

Washington is not split from Oregon. Puget Sound is part of British Columbia (again its much more rural), with southwestern Washington in Oregon and Eastern Washington attached to either Oregon or Idaho. There is no state capital in Olympia. British Columbia gets another two dozen more MPs, nearly all of these going to the Conservatives since ITTL BC is more consistently Conservative. All but a couple members of Washington's House of Representatives delegation go to Oregon, with Idaho picking up one or two extra Congressmen if it gets Eastern Washington, and, since the population of the US is lower by a couple million, whichever state just misses picking up another Congressman in any particular Census gets that Congressman. In 2010, the first bubble state was North Carolina, which would have gained a fourteenth Congressman, then Missouri, which might have kept its ninth Congressman. The political complexion of neither Oregon nor Idaho winds up changing that much.

States tend to be admitted to the union in pairs. Looking up the dates of admission to states to the union, the only clear exceptions to this rule that I found were Vermont, after which there has almost always been an even number of states, Ohio, Louisiana, New Mexico, and Oklahoma. Washington was admitted in 1888-9 as part of a block of six states, the others being North Dakota, South Dakota, Wyoming, Montana, and Idaho. The Republican Congress of that time was not doing some gerrymandering with state admissions, the effects of which are still with us today, which is why there are two Dakotas and Wyoming is not part of Montana. They might have admitted an oddly-shaped, under populated Washington anyway. They might have also moved up the admission of New Mexico. My guess is that Idaho would have been split, with IOTL eastern Washington and northern Idaho forming a state, and the southern two thirds of Idaho becoming Idaho. What is now southwestern Washington would have remained with Oregon. The eastern Washington/ northern Idaho state would still have a larger population than either Dakota, Montana, Wyoming, or Idaho. It probably would have been called "Washington" but I have no idea where the state capital would be (no, not Spokane, state capitols are almost never in the state's largest city).

Olympic National Park and Mt. Rainier are part of the Canadian national parks system.

Your numbers are a bit off considering the city of Vancouver has 600,000 people alone and the greater Vancouver metropolitan area has 2.4 million people and Vancouver is a busier port than Portland otl

 

[Galba Otho Vitelius]

"Your numbers are a bit off considering the city of Vancouver has 600,000 people alone and the greater Vancouver metropolitan area has 2.4 million people and Vancouver is a busier port than Portland otl"

I meant the portion in the state of Washington. I took the latest population estimate for the state of Washington, which is seven million, and deducted my rough estimates for eastern and southwestern Washington.

But my argument is that ITTL this area is not as developed as it now is, because Portland becomes the main American port in the Pacific Northwest and gets most of the development that happened with Seattle. The Canadians are not interested in Seattle as a springboard to Alaska, nor will put military bases nor Boeing there. All that goes to Portland and Seattle is a sleepy Canadian lumber town, though it may attract some retirees later.

 

[JackLumber]

"Your numbers are a bit off considering the city of Vancouver has 600,000 people alone and the greater Vancouver metropolitan area has 2.4 million people and Vancouver is a busier port than Portland otl"

I meant the portion in the state of Washington. I took the latest population estimate for the state of Washington, which is seven million, and deducted my rough estimates for eastern and southwestern Washington.

But my argument is that ITTL this area is not as developed as it now is, because Portland becomes the main American port in the Pacific Northwest and gets most of the development that happened with Seattle. The Canadians are not interested in Seattle as a springboard to Alaska, nor will put military bases nor Boeing there. All that goes to Portland and Seattle is a sleepy Canadian lumber town, though it may attract some retirees later.

Ahh makes more sense then, my mind jumped straight to the Canadian side of the border and yeah your right Seattle probably won't amount to much ITTL

 

[Shevek23]

I think we'd have to game out the TL to judge whether Britain getting Puget Sound would depress that region's population versus OTL or not. Certainly Britain has plenty of people who might want to emigrate there, and like the rest of Canada there is little to stop Yankees from moving in--they have to take an oath to the monarch or something I guess but I don't think that has ever done much to slow down people moving back and forth across the border OTL. What might stop Yankee settlers is British policy, especially if the HBC has strong influence in shaping that policy! But I expect sooner or later the region is gradually opened for settlement. Perhaps with absolute limits set more stringently than US settlement policy on behalf of Natives with treaty rights.

Thinking more about it, these are the major reasons to expect lower population density than OTL--HBC interests, and Native rights being better protected.

Otherwise I'd think the region would be developed to capacity.

What an ATL British Puget Sound region might do instead is be as densely settled as OTL Washington in those parts, but siphon off settlers north of the OTL borders. Vancouver itself will surely develop into a great city, but its hinterland, especially away from the city and up into the mountains, might suffer.

I expect a split result, OTL US soil ceded being less populated due to strong Native rights, OTL BC being about as OTL, the whole thing much bigger than OTL BC. I expect something of a bandwagon effect--that OTL prospective settlers may have passed BC by because the British controlled and settled area was limited, needing to cross the border into Yankee land for elbow room (in easy terrain I mean). Whereas with that elbow room annexed, more people might be drawn to the colony as a whole since it is bigger, not just to OTL limits but perhaps beyond a bit.

But of course this assumes the region finds economic niches at least as lucrative as OTL. As part of the British Empire, then Commonwealth, one might expect fairly good opportunities--but of course as British soil, the place is back of beyond, as much so almost as Australia, and unlike Australia the USA is sitting right there sucking up the oxygen. The USA is opportunity to an extent, but also is somewhat in the way of regional development. Certainly I suspect BC if that is what it winds up being called would be better off as part of Canada than its own dominion. But being a Dominion on its own might mean some ATL opportunities.

Now I see that the argument of Puget Sound underdevelopment relative to OTL applies to the city of Seattle itself, not so much the region agriculturally. Of course you're right that means a big hit in population--on the other hand, there might be some spillover from a greater Vancouver that fosters more urban development, perhaps not concentrated in Seattle's site but all along the Sound shores.
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If the Americans don't have a port in Puget Sound there isn't really a point in fighting with Britain over the Columbia River as a border. That was a huge portion of the dispute.

Could you elaborate? If the USA concedes the Sound territories, it becomes all the more important to guarantee the USA controls both banks of the Columbia I'd think, at least up to the Willamette confluence--east of there perhaps making the river the border is OK. But the Columbia mouth becomes the USA's only good port on the Pacific, unless the Yankees later conquer or otherwise obtain California. If a potentially hostile British colony controls the entire north shore, then Portland's utility as a naval base is limited--it might be possible to build up one of the lesser ports of the Oregon coast farther south, with over-hill roads and railroads as a lifeline and large scale trade and development happening coastwise via the Columbia in peace time. But wouldn't it be smarter for the US negotiators to argue that in giving up the whole Sound, the USA ought to get a port it can completely control out of the deal?

Perhaps it is not necessary for the north shore to be completely normal US land--the treaty could establish that it is US soil, in no way British, but the US agrees to keep it in perpetuity as a Native reserve, with only minimal outposts on the shore and none away from it, so in effect the territory serves as a Neutral zone, a buffer to prevent US and British settler communities from bumping into each other. HBC might also be granted special rights to trade there, which also gives HBC a foot in the door of the US Oregonian markets. The point is to exclude both US and British military power from there; then the south shore of the Columbia can be safely developed as a Naval asset without it being under immediate British threat, and there are no Yankee Army camps right across the southern British border either. Americans observing Native treaty rights monitor the zone via Indian agents and hopefully develop cordial relations with the peoples there; HBC representatives are the eyes and ears of Britain in the zone; nobody can do anything funny without setting off alarms and as long as everyone follows the treaty, trouble cannot brew on the border.

Of course as I mentioned before, US citizens might infiltrate into British territory and some might wish to pull a Texas; also OTL as I have mentioned natural born British subjects were not always paragons of loyalty to the Crown either. But I think even if some uprising in the region casts out effective British control and raises a cry for US annexation, the Americans back East are not going to be so daft as to insult the British by doing so. I could see the US government rather playing the role of mediator, undertaking by treaty never to annex the lands conceded in the 1820s treaty, but also stipulating that British control must be contingent on the will of the majority of settlers, not imposed where it is not wanted, and thus negotiating an independent Cascadian nation.

I view that as a very low probability outcome and it might trigger war between the USA and Britain anyway. But I thought I might mention it.

 

[The Gunslinger]

If America decides to offer the whole sound, the Columbia River is the logical border. The British already control everything of value on their side of the river, and they can push the claim that because David Thompson was the one to successfully navigate it they've got the much stronger claim. All of this is prior to the age of steam in a region that was virtually unexplored, so nobody negotiating knows if there are viable ports on the Columbia or if the Willamette Valley is really great yet. These are all things that will happen decades into the future. In 1818, if the American offer up the sound and the British accept, the Columbia is where the border probably goes as it's the only thing anybody has a good grasp of where it actually is.

A lot of things change with a firmly demarcated line in the Oregon. The fur trade being the big one. The Indians will start to see a small trickle of trappers in the area and there will eventually be violence. The Indians were long established in the region and at some point violence is going to erupt because the American traders don't have the reputation of the HBC or political acumen to deal with the Indians. In OTL the HBC policy was to make the area a 'fur desert' and hunt everything to the point of collapse to keep out the American trappers, which worked until farmers showed up and the HBC decided that there was money to be made keeping these people from starving to death.

Secondly, there will be British forces in the area because there's now a firm demarcation. In OTL, the HBC was the only game in town because neither side was permitted military incursions. So in case the Americans try to cross the border without permission the answer is probably 'sod off' and the Americans are sent packing. If the American army is anything like OTL they'll have almost nothing in the area, be badly equipped and probably have hostile Indians on their hands and suffer from desertion from the lousy pay. The British will also have trouble with these things too, but less serious.

My 'broad strikes' changes is basically settlement patterns. The Willamette Valley was the first place settled by the Americans because it was close to Fort Vancouver (where they desperately needed supplies to not die upon arrival). So if the Americans have their string of forts in the area early settlements probably spring up around those. There will probably be more hostility from the natives towards the early settlers because they're not HBC employees this go around. Portland doesn't take off until the 20th century because it's just too far away from anything of note. All of American politics is up in the air because Polk might not win the election, but Tyler may not ever get a shot at the presidency if Harrison doesn't die. Crawford may not have his stroke and win in 1824 too, you can do whatever you want.

BC probably joins Confederation because they'll likely still have the spending program of OTL. Vancouver is bigger because of the lack of a 'proper' American port in the area. I'd give a very hard maybe about Vancouver Island maybe being split off from mega-BC because fears from Quebec and Ontario.

Other than that not much changes. Britain and America are probably on slightly better terms, and the HBC shares are worth a little less.

 

[EnglishCanuck]

It's an interesting POD, and one could see it pushing the border south of the 49th to the 46th given this changed TL if the British have a larger (relatively speaking) presence in the Willamette earlier on. This means that they could push somewhat inland, and unlike OTL where the gold rushes of 1850s-60's didn't really attract population due to the rough roads, wilderness, and ect, you have probably a much larger settler population arriving to fill the Valleys or take advantage of local fishing, ect. This means that if/when Canada confederates BC has a much larger territory and population, and perhaps more southerly interests on the Great Plains.

Much less straight border for the whole region that's for certain.

 

[Shevek23]

Willamette? That means you're envisioning US ceding Oregon as well as the northern territory?

That goes too far. The USA might lose Oregon in a war, most likely having to trade it away at a peace settlement, but I don't think we'd ever voluntarily concede our sole outlet on the Pacific. And the Columbia mouth is essential to that, and I've suggested the need to control both shores, so British Willamette is a different scenario, one of British conquest and victory.

Perhaps you just mean to suggest that just as I think there'd be a fair number of Yankees settling in British Puget Sound, so there would be some British immigrants in US Oregon? Surely some, we had a lot of British immigrants settling all across the USA OTL. Many more? Well, why go to Yankee-crowded Oregon when greater BC has so much to offer?

Only if Greater BC becomes overcrowded.
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Or are you just mixing the Willamette up with some other body of water?

 

[EnglishCanuck]

Willamette? That means you're envisioning US ceding Oregon as well as the northern territory?

That goes too far. The USA might lose Oregon in a war, most likely having to trade it away at a peace settlement, but I don't think we'd ever voluntarily concede our sole outlet on the Pacific. And the Columbia mouth is essential to that, and I've suggested the need to control both shores, so British Willamette is a different scenario, one of British conquest and victory.

Perhaps you just mean to suggest that just as I think there'd be a fair number of Yankees settling in British Puget Sound, so there would be some British immigrants in US Oregon? Surely some, we had a lot of British immigrants settling all across the USA OTL. Many more? Well, why go to Yankee-crowded Oregon when greater BC has so much to offer?

Only if Greater BC becomes overcrowded.
--------
Or are you just mixing the Willamette up with some other body of water?

I'm assuming the British push south into the Williamette post 1818, but if that's too far I stand corrected.

However, I do think that if all of modern Washington was ceded in 1818 the British could stand a chance of pushing south of the river since settlement patterns would still be up in the air. Though they may push east instead which would still push the border much further south that OTL.

 

[Agent_J]

The Gunslinger is correct. The Columbia River is the logical border and that was what was offered by Gallatin and Rush as noted by Frederick Merk, "all the territory draining west from the Cascade divide and north from the Columbia River divide into the gulf". I've updated the OP.

 

[The Gunslinger]

It's an interesting POD, and one could see it pushing the border south of the 49th to the 46th given this changed TL if the British have a larger (relatively speaking) presence in the Willamette earlier on. This means that they could push somewhat inland, and unlike OTL where the gold rushes of 1850s-60's didn't really attract population due to the rough roads, wilderness, and ect, you have probably a much larger settler population arriving to fill the Valleys or take advantage of local fishing, ect. This means that if/when Canada confederates BC has a much larger territory and population, and perhaps more southerly interests on the Great Plains.

Much less straight border for the whole region that's for certain.

Did the 1818 not decide the 49th parallel?

 

[Agent_J]

Indeed it did. Treaty of 1818.
Article II set the boundary between British North America and the United States along "a line drawn from the most northwestern point of the Lake of the Woods, [due south, then] along the 49th parallel of north latitude..." to the "Stony Mountains"[3] (now known as the Rocky Mountains). Britain ceded the part of Rupert's Land and Red River Colony south of the 49th parallel (including the Red River Basin — which now forms parts of Minnesota, North Dakota, and South Dakota — as well as a small piece of modern-day Montana near Triple Divide Peak). The United States ceded the small portion of the Louisiana Purchase that lay north of the 49th parallel (namely, parts of the Milk River, Poplar River, and Big Muddy Creek watersheds in modern-day Alberta and Saskatchewan).

 

[EnglishCanuck]

Did the 1818 not decide the 49th parallel?

Indeed it did. Treaty of 1818.
Article II set the boundary between British North America and the United States along "a line drawn from the most northwestern point of the Lake of the Woods, [due south, then] along the 49th parallel of north latitude..." to the "Stony Mountains"[3] (now known as the Rocky Mountains). Britain ceded the part of Rupert's Land and Red River Colony south of the 49th parallel (including the Red River Basin — which now forms parts of Minnesota, North Dakota, and South Dakota — as well as a small piece of modern-day Montana near Triple Divide Peak). The United States ceded the small portion of the Louisiana Purchase that lay north of the 49th parallel (namely, parts of the Milk River, Poplar River, and Big Muddy Creek watersheds in modern-day Alberta and Saskatchewan).

Well looks like I was wrong!

For some reason I'm always thinking the 49th parallel was chosen in 1846!