
I came across this nifty analysis from the New Scientist (not an endorsement as they're Global Warming coverage seems a bit biased). Click on the graphic for a larger view - the darker the color of the land, the more "remote" the location is. The study included various modes of transportation including rivers (why the Amazon isn't as remote as one might think), rails, roads, etc. and how far it would be to a "major" city - defined as one with a population of 50,000 people or more.