Political Borders

The border between North and South Korea is the most heavily guarded and hostile in the world. The border stretches from the Pacific Ocean to the Korea Bay roughly along the thirty-eighth parallel north. Korea relies heavily on China for trade, but in late 2011, the North Korean government temporarily shut the border between the two countries in order to prepare for Kim Jong-Il's funeral.

Citations: http://www.pbs.org/wnet/wideangle/episodes/border-jumpers/the-worlds-most-complex-borders/north-koreasouth-korea/2337/; http://online.wsj.com/article/SB10001424052970204058404577110380555673036.html