Today I tuned into www.fivethirtyeight.com, one of my favourite sources for quantitative analysis of US electoral trends.
What do I see in the top-of-page banner advertising? An advertisement for the British Liberal Democratic Party. Clearly the advertising system has made an (accurate) guess of my geo-location and served up content to match. Although my subject matter interest is US politics, the advertising market is segmented by geo-location of end-user rather than the geography of the subject under discussion.
My point is this: if the Internet is truly "borderless" then this should not be possible.
Conclusion: the Internet has borders.