There are now 63 borders where walls or fences separate neighboring countries - nearly quadrupling in just 15 years. Most of the new walls are being erected within the European Union, which until recently was nearly borderless. This new age of barriers is not just about chain links and concrete. Most of the border land here is still unfenced. A completed border barrier would have to navigate these natural challenges.

Source: New Zealand Herald October 13, 2016 00:33 UTC