The area has seen a huge influx of Border Patrol agents, but officers like Green fear the government will always be behind the curve in dealing with sophisticated smuggling operations.
"If the Border Patrol puts more people in the ground, they will take to the mountains," Green said. "We are always playing catch up."
MCALLEN, Texas: In bicultural region, residents root for reform as the path to "secure"
Some 800 miles southeast of El Paso is the Rio Grande Valley, where rapid growth has overtaken sugar cane and cotton fields and sleepy hamlets are now thriving cities. More than 1.2 million people live in the two border counties on the U.S. side of this southernmost tip of Texas, and a similar number are directly across the border anchored by the sprawling cities of Matamoros and Reynosa.
Here, illegal crossers can quickly slip into communities without being forced to trek for days through wide-open spaces.
Part of the solution was the border fence, and 400 landowners — most of them in this part of Texas — had property seized to build it. The fence divided people from swaths of their own land, but also struck many as an offensive gesture in this bicultural, bilingual region that views itself as one community with its Mexican sister cities.
More effective, locals said, has been the influx of Border Patrol agents — 2,546 in the Rio Grande Valley today, almost seven times more than 20 years ago.
And while some agents still patrol on horseback, others are aided now by night-vision goggles and unmanned Predator drones watching from 19,000 feet overhead with high-powered infrared cameras.
Definitions of a secure border vary here, but there's agreement that the premise should not stand in the way of immigration reform.
Tony Garza remembers watching the flow of pedestrian traffic between Brownsville and Matamoros from his father's filling station just steps from the international bridge. He recalls migrant workers crossing the fairway on the 11th hole of a golf course — northbound in the morning, southbound in the afternoon. And during an annual celebration between the sister cities, no one was asked for their papers at the bridge. People were just expected to go home.
Garza, a Republican who served as the U.S. ambassador to Mexico from 2002 to 2009, said it's easy to become nostalgic for those times, but he reminds himself that he grew up in a border town of fewer than 50,000 people that has grown into a city of more than 200,000.
The border here is more secure for the massive investment in recent years but feels less safe because the crime has changed, he said. Some of that has to do with transnational criminal organizations in Mexico and some of it is just the crime of a larger city.
Reform, he said, "would allow you to focus your resources on those activities that truly make the border less safe today."
Monica Weisberg-Stewart was born and raised an hour upriver in McAllen. Her father ran a store downtown that she runs today, filled with socks, underwear and jewelry. She echoes Garza's assessment that things feel less safe now but says that has more to do with the area's growth than with what's happening in Mexico.
"I thought that this was definitely the best place to raise my family," she said, "and I still believe that to be true today."
Hidalgo County Sheriff Lupe Trevino points out that drug, gun and human smuggling is nothing new to the border. The difference is the attention that the drug-related violence in Mexico has drawn to the region in recent years.
He insists his county, which includes McAllen, is safe. The crime rate is falling, and illegal immigrants account for small numbers in his jail. But asked if the border is "secure," Trevino doesn't hesitate. "Absolutely not."
"When you're busting human trafficking stash houses with 60 to 100 people that are stashed in a two, three-bedroom home for weeks at a time, how can you say you've secured the border?" he said.
Trevino's view, however, is that those people might not be there if they had a legal path to work in the U.S.
"Immigration reform is the first thing we have to accomplish before we can say that we have secured the border," he said.
NOGALES, Ariz.: In nation's busiest illegal corridor, ranchers scoff at "secure"
Everywhere he goes on his cattle ranch, Jim Chilton has a gun at the ready. He has guns at his front door, guns in his pickup truck, guns on his horse's saddle. His fear? Coming across a bandit or a smuggler on his land northwest of Nogales, Ariz.
Cattleman Gary Thrasher frequently encounters immigrants and smugglers running through his property. Some have showered in his barn. He and his family live in constant dread.
"They really have secured the towns right along the border, but what that does is it drives all the traffic out into the rural areas around here," said Thrasher, a rancher and veterinarian for more than 40 years on the border east of Douglas, Ariz. "It sends the traffic right into our backyards."
The question of border security hits close to home to those who work the land in southern Arizona. It was here, in 2010, that cattle rancher Robert Krentz was gunned down while checking water lines on his property near Douglas. Local authorities have said they believe the killer was involved in smuggling either humans or drugs.
That same year, Border Patrol agent Brian Terry was killed in a shootout near Nogales with Mexican gunmen that brought attention to the federal government's botched weapons-trafficking probe called "Fast and Furious."
"The border is not secure," said Chilton. "Period. Exclamation mark."
Defining "secure border" in Arizona is never easy. Just last week, U.S. Sen. John McCain hosted two town hall meetings on immigration reform in his home state, and was left defending a plan he's been developing.
During a heated gathering in the Phoenix suburb of Sun Lakes, one man yelled that only guns would discourage illegal immigration. Another man complained that illegal immigrants should never be able to become citizens or vote. A third man said illegal immigrants were illiterate invaders who wanted free government benefits.
McCain urged compassion. "We are a Judeo-Christian nation," he said.
The crackdowns in Texas and California in the 1990s turned Arizona's border into the busiest for human smuggling for 15 years running now.
In 2000, agents in the Tucson sector made more than 616,000 apprehensions — a near all-time high for any Border Patrol sector. The number eventually began dipping as the agency hired more than 1,000 new agents and the economy collapsed. State crackdowns such as the "show me your papers" law — requiring police enforcing other laws to question the immigration status of those they suspect are in the country illegally — are also thought to have driven migrants away.
The result: the sector had 120,000 apprehensions in fiscal 2012.
But the amount of drugs seized in Arizona has soared at the same time. Agents confiscated more than 1 million pounds of marijuana in the Tucson sector last year, more than double the amount seized in 2005.
In Nogales, Sheriff Tony Estrada has a unique perspective on both border security and more comprehensive immigration reform. Born in Nogales, Mexico, Estrada grew up in Nogales, Ariz., after migrating to the U.S. with his parents. He has served as a lawman in the community since 1966.
He blames border security issues not only on the cartels but on the American demand for drugs. Until that wanes, he said, nothing will change. And securing the border, he added, must be a constant, ever-changing effort that blends security and political support — because the effort will never end.
"The drugs are going to keep coming. The people are going to keep coming. The only thing you can do is contain it as much as possible.
"I say the border is as safe and secure as it can be, but I think people are asking for us to seal the border, and that's unrealistic," he said.
Asked why, he said simply: "That's the nature of the border."
Spagat reported from San Diego; Llorca from El Paso, Texas; Sherman from McAllen, Texas; and Skoloff from Phoenix. Also contributing to this report was AP writer Cristina Silva in Phoenix.