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One third of the population of Switzerland lives within 5 kilometers of the main train line crossing the country
(reddthat.com)
Source (yes sorry it's LinkedIn, if you any another one, I'll update): https://www.linkedin.com/posts/prof-stefan-michel_notsweden-train-activity-7210174690827370496-8iJz?utm_source=share&utm_medium=member_ios
I bet US can get something similar for NE corridor
Not as big a portion of the country, but yeah coastal areas will often have a large population living in roughly a line.
In North America I believe the line connecting the most people would go from Quebec City through Montreal, Ottawa, Toronto, London, Detroit, Chicago, Milwaukee and Minneapolis (though maybe not within just 5 km of it). This is the most populous part of the Great Lakes Megalopolis and into the St. Lawrence.
Switzerland is about as big as Vermont and New Hampshire.
NE corridor is 100m people
for real, more people live in new york alone than do in finland
Could be, feel free to post a similar study on that region if you find one!