According to published reports, Mexican drug cartels clear some $30 billion a year on marijuana, cocaine, heroin, and methamphetamine moved over the border into the United States – more than the annual gross domestic products of Panama, El Salvador, Nicaragua, Honduras, or Belize – indeed, more than the last three combined. They further bolster their incomes through kidnappings in Mexico (up 317 percent in the last six years) and human smuggling.

With an annual illegal drug consumption level estimated at $65 billion, America is so lucrative to the drug lords that they have been able to create vast armies, drawn largely from Mexico’s poorest, who earn less than $10 a day in legitimate work. Officials in Mexico’s largest state, Chihuahua, which borders New Mexico and Texas, estimate more than 10,000 citizens in the city of Juárez alone work for the cartels.

In 2010, the cartels spent an estimated $2.75 billion – less than 10 percent of that year’s drug profits – bribing Mexican police and other officials. Given that the vast majority of violent crimes in Mexico are never solved, the bribes, combined with threats, kidnappings, and murders – part of the cartels’ infamous “plata o plomo” (silver or lead) ultimatum – appear to have accomplished their goal.

Since President Felipe Calderón took office in Mexico in 2006 and declared war on the cartels, an estimated 40,000 Mexicans have died in drug-related violence – nearly half of them law enforcement or judicial – a sixfold increase from the previous five years. The six identified major cartels, along with dozens of smaller gangs, responded to Calderón’s military offensive with a major arms race, acquiring everything from assault rifles (some unwittingly provided by the United States in an attempted weapons sting gone disastrously wrong) to rocket-propelled grenades. Those are used not only against law enforcement, but also on each other in the bloodiest “turf war” in North American history.

The number of mass graves uncovered in one of America’s largest trading partners is so great that a senior human rights commission official in the northern desert state of Durango recently warned, “The world should be as worried about what’s happening here as they are about what’s happening in North Africa.” It is believed the gang-related death toll in Mexico now exceeds the number dying in the ongoing war in Afghanistan.

Calderón, whose single six-year term as president ends in 2012, has had some successes, but not enough to end the violence or trafficking. He and the Mexican legislature have been working on fundamental changes in the structure and practices of the police and judiciary, similar to those made by Colombia in the 1990s that helped reverse what then appeared to be an inevitable transition into a narco-state.

While the type of violence plaguing Mexico has yet to cross the border, it has raised concerns among both the general population on the U.S. side and those tasked with protecting America – the Coast Guard, state National Guards, U.S. Northern and Southern Commands, FBI, DEA, ATF, CIA, state agencies such as the Texas Rangers, local police and sheriffs’ offices, and prosecutors and judges at all levels.

But perhaps no agency is more fully exposed on the front lines than Customs and Border Protection (CBP), and specifically, its U.S. Border Patrol (USBP).

“What happens in Mexico or Canada is something we assess on a continuous basis, taking two fundamentals into consideration – the threat and the vulnerabilities,” Border Patrol Chief Mike Fisher told The Year in Homeland Security. “So over the years, we not only have seen and assessed what has been happening, especially in Mexico, but adjusted our strategies and capabilities to meet that.

“We have increased Border Patrol agents, detection capabilities, and infrastructure, including miles of fence and roads that give us access we did not have before. Our capability as a law enforcement organization within the Department of Homeland Security [DHS] is stronger than ever. We have coupled that with what is happening in northern Mexico and, much to the Mexican government’s credit, the stand and commitment they have brought to this fight.”

When he was an agent patrolling the border 20 years ago, Fisher recalled, it was not unusual for smugglers on the verge of capture to simply abandon whatever they were smuggling and flee back into Mexico, where there was no one waiting to arrest them.