Along the border between the U.S. and Mexico, armed groups on patrol — mostly men — look for illegal immigrants and drug traffickers. They're not U.S. Border Patrol, but regular people who've decided to take matters into their own hands.
They call themselves militias. Groups such as these have been around for decades, but they exploded in number after Barack Obama was elected president. Today, there are 276 militia groups around the country, according to the Southern Poverty Law Center.