Awesome job, Eric!
One thing though - the border crossing on foot is legal. I inquired about this years ago and the rule (as I recall) is you must cross the border by car at a checkput going into Canada and coming back, you may then enter the backcountry on foot, but you may not go all the way to a road and must return the way you went in. Source: a NP ranger at NCNP.
If you call border control, they will tell you it's illegal, but if you push them, they will refer you to the NPS.
Also, just think about this logically: why is there a TH marker with a register if it is illegal? I have seen that register replaced in the past. I've also seen the trail cleared/maintained, and have heard the NPS does patrol that trail, entering from Canada. Moreover, if you call for. a permit in the area, and tell them you are not coming from the US side and not entering Marblemount, you will be issued an overnight permit. If it was illegal, why would they do that?
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