Where are the migrants from?
El Salvador, Guatemala, and Honduras. Until recently, most people crossing the Mexican border illegally into the U.S. were Mexicans looking for work. But in the past two years, the net migration from Mexico has become essentially zero. That's partly because Mexico's economy has improved; at the same time, the government crackdown on drug gangs there has finally eased the violence. Unfortunately, the success of Mexico's crackdown — and another "war on drugs" in Colombia — has shifted some of the trafficking business to El Salvador, Guatemala, and Honduras, where it has fueled the growth of violent gangs. Gangs now run entire towns, murder and rape almost at will, and force families and businesses to pay protection money. "For many people, the choice is to flee or to die," says Carlos Paz, a charity director in Honduras.

Who are these gang members?
Most of them were deported from the U.S. Beginning in the late 1990s, a new U.S. immigration law provided for noncitizens, even longtime residents with green cards, to be deported if they committed any kind of crime. Authorities began using the policy to crack down on Los Angeles street gangs, particularly MS-13, a tough gang started by Salvadorans that included Hondurans and Guatemalans, and MS-18, an originally Mexican gang that recruited Central Americans. More than 100,000 of these gang members were deported from 2001 to 2010 on the planes made famous in the movie Con Air. Many had come to the U.S. as small children, and when they were sent back to their home countries, they had few connections and no prospects, so they banded together in criminal gangs, with tactics and ruthlessness they learned on the streets. "This American style of gangsterism was imported like a catalyst," says Al Valdez, former head of the gang unit for the district attorney in Orange County, California. "It took off like a wildfire, like a virus out of control."

What is life like there now?
The new gangs are dealing arms and drugs and engage in widespread extortion, demanding payments from local businesses and individuals; those who do not comply are murdered, tortured, or raped. The weak and corrupt governments of the three countries simply couldn't cope with this new breed of organized crime, and police were co-opted or cowed into submission. In El Salvador, children as young as 7 are forced to work as lookouts or couriers for gangs, and they are killed if they refuse. Honduras now has the highest murder rate in the world, and San Pedro Sula, where most Con Air flights landed, is the world's most violent city, with a murder rate of 187 per 100,000. (The U.S. rate is 5 per 100,000.)

How did the exodus begin?
People came to believe it was safer to risk an illegal journey over hundreds of miles than to stay. So smugglers known as coyotes began doing big business trafficking Central Americans across borders. Last fall, they began spreading rumors that any child who made it across the U.S. border would be automatically granted asylum. The story was rooted in a kernel of truth: Under a law passed by Congress and signed by President Bush in 2008, unaccompanied children from Central America can't be deported without a hearing, and that process usually takes at least a year. Another source of the rumors was President Obama's 2012 executive order ending the deportation of young illegal immigrants who'd been living in the country for at least five years. As a result of the rumors, Central Americans who had already migrated to the U.S. began paying coyotes to bring their kids to them. Parents still living in Central America began rushing to send their kids north now, before the U.S. changed its policy.

What is being done in Washington?
Not much thus far. The Obama administration has asked Congress for $3.7 billion in extra funds to house about 57,000 children temporarily and hire more immigration officers and staff to process their requests to stay. The White House says most of the migrants "would not qualify for humanitarian relief" under the 2008 law and would be deported once they have hearings. House Republicans refused to act on Obama's request and before leaving for their August recess passed a bill last week that would change the 2008 law so that Central American children could be sent back quickly. The bill has no chance of passing the Senate or becoming law. The impasse leaves the migrants in legal limbo — and the U.S. with no coherent policy for dealing with the exodus from Central America.

One child's story
Most children classified as "unaccompanied" by parents are actually traveling with adults they know, cousins or village friends. But some — like Dayanna, a 9-year-old from El Salvador who made the journey in June — travel with strangers. After the drug gang that runs her Salvadoran neighborhood demanded protection money from her grandmother and threatened to hurt her, Dayanna could no longer leave the house to go to school. Her parents, undocumented workers who live near Boston, paid a coyote $4,500 to bring her to them. The little girl was shunted on buses and trucks, hungry and unable to sleep, on a journey that took more than a week. During one stop, "a guy that wasn't with our group tried to rape the girl who was taking care of me," she told The Boston Globe. "I started to hit and kick him; then the other guys kicked him out." Once they got through Mexico, the traffickers stuck Dayanna in an inner tube and floated her across the Rio Grande, where she was fished out by waiting agents from the U.S. Border Patrol. The girl has been reunited with her parents while awaiting a hearing on whether she can stay. "We never want to be separated from her again," her mother, Guadalupe, said. "We are in the hands of the government now."