Looking at the map I only just noticed how small the BC coastline is and how Alaska takes most of it. Looks like it goes back to agreement between England and Russia https://en.wikipedia.org/wiki/Treaty_of_Saint_Petersburg_(18... And there were never more than 700 Russians in Alaska. https://en.wikipedia.org/wiki/Russian_America#Sale_of_Alaska...
Canada and the UK worried in the late 1940s that Newfoundland—at the time, planning to regain self-government after 15 years under British stewardship—would want to join the US, which the island historically has had the most commercial links with. Canada didn't have much trade with Newfoundland, but didn't want the US to essentially blockade its east the way Alaska already blockaded its west. Thus, when referendums were set up to give residents a choice of what to do, only the options of self-government, continued British rule, or joining Canada were listed.