Well perhaps, but my point was that its still a lot bigger than those in Oregon campaigning for the other route.
Agreed, and in fact they will win out - sort of....
Chicago->Seattle/Columbia
Gotcha - other than the question of final destination (Seattle/Columbia/San Francisco) that's really the only route under serious consideration by the USA.
Were any these existential, difficult, or impinging on the common man to even a fraction of the extent of the war of 1812?
The Indian war in the Old Northwest was pretty difficult. But no, nothing so serious as the War of 1812. On the other hand, the Americans are pretty cocky since they haven't had a serious military disaster since the ARW, either.
Well you can't quite have it both ways - either Americans are flooding the west and the DSA is worried and the US isn't, or the Americans aren't and the worry goes the other way round.
Actually I think I can - the Americans are currently more numerous than the British on the West Coast, mostly due to earlier identification of overland routes and earlier claims to the territory. Both the British and the Americans have access to the Mexican Isthmus for transport as well, so that's a wash.
So the British are worried that the Americans will overgrow their territory on the Pacific Coast if this goes on, thus the Railroad. The Americans once they hear that there will be a British Transcontinental Railroad become concerned that this will reverse the historical trend and in fact it will then be the British who threaten to overgrow their territory and encroach on the Americans - backed by the Royal Navy!
Yes, but the Federal government taxes imports, so higher tariffs result in less imports and in them having less cash,
Yes and no. If the Tariffs are too high, it shall be as you say. But if they are just modestly higher, than they won't too badly retard trade and lead to increased governmental revenue.
and wealth distributed to farmers is just going to spur midwestern demand and local railroads (the chicago radial network mostly),
Fair point. And they want this, but private ventures are meeting this demand mostly without recourse to government support (except for right-of-way, of course).
where you need to put the wealth is with urban capitalists and industrialists who can make the investment and want to export to the pacific
And they have access to that.
Also if they are worried about the DSA won't they be spending more on armaments?
They are more worried at this point about being out-competed than outright war, though if it becomes clear that one side or the other has won the economic/settlement competition, the loser might just compensate by increased armament.
Plus there is still the issue of the lakes improvements - won't the Canadians be clamouring for a seaway and so on?
There already is one - remember that Canal building was also about a decade ahead of OTL. Now the 'Canadians' want to link their waterways with the west, so they too are in favor of a railway going to the Pacific.