4. Southern Sudan - Sudan Border
UNHCR staff assist refugees arriving at the Doro camp in South Sudan, close to the border with neighbouring Sudan. Nearly 50,000 refugees have arrived here in recent months. (Robert Stansfield/UKGov)
After Southern Sudan seceded from Sudan officially in July of 2011, Sudan launched a military campaign, claiming that Southern Sudan had ambushed its forces. The campaign displaced some 100,000 people from Sudan's southern border state and dozens were killed in bombings. More than 1.5 million people died in Sudan's 22-year civil war which ended in 2005. The United States lifted economic sanctions on Southern Sudan last year, but has renewed its sanctions on neighboring Sudan, which have been in place since 1997.
5. U.S.- Mexico Border
Vehicles are parked along the border fence as pedestrians cross the street in Nogales, Mexico. (AP Photo/Ross D. Franklin)
The nearly 2,000-mile border is one of the most dangerous in the world, because of both drug cartel related violence and the desert conditions that have led to the border-crossing deaths of thousands of Latin Americans seeking to work in the United States. More than 47,000 deaths have occurred in Mexico due to cartel violence since 2006, with more than half of those deaths occurring in border states. And according to The New York Times, an estimated 150 to 250 people die every year trying to cross the U.S.-Mexico border.