SELLS, Ariz. -- An eerie hush settles in at sundown on the Tohono O'odham Nation, which straddles 75 miles of border with Mexico.
Few residents leave their homes. The roads crawl with the trucks of Border Patrol agents, who stop unfamiliar vehicles, scrutinize back roads for footprints and hike into the desert wilds to intercept smugglers carrying marijuana on their backs and droves of migrants trying to make it north.
By the bad luck of geography, the only large Indian reservation on the embattled border is caught in the middle, emerging as a major transit point for drugs as well as people.
A long-insular tribe of 28,000 people and its culture are paying a steep price: the land is swarming with outsiders, residents are afraid to walk in the hallowed desert, and some members, lured by drug cartel cash in a place with high unemployment, are ending up in prison.
"People will knock on your door, flash a wad of money and ask if you can drive this bale of marijuana up north," said Marla Henry, 38, chairwoman of Chukut Kuk district, which covers much of the border zone.
The tightening of border security to the east and west, which started in the 1990s and intensified after the Sept. 11 attacks, funneled more drug traffic through the Tohono O'odham reservation, federal officials said, and especially more marijuana, which is hard to slip through vehicle crossings because of its bulk.
A record 319,000 pounds of marijuana were seized on the reservation in 2009, up from 201,000 pounds the previous year, along with small amounts of cocaine, heroin and methamphetamine.
Hundreds of tribal members have been prosecuted in federal, state or tribal courts for smuggling drugs or humans, taking offers that reach $5,000 for storing marijuana or transporting it across the reservation. In a few families, both parents have been sent to prison, leaving grandparents to raise the children.
"People are afraid that if they say no, they'll be threatened by the cartel," Ms. Henry said.
If residents of remote villages tried to call the police, she said, help might not arrive for two hours or more.
At the same time, some residents are angry at the intrusion of hundreds of federal agents, including some who stay for a week at a time on bases in remote parts of the reservation. The surge in agents who cruise the roads has meant more checkpoints and tighter controls on a border that tribal members, 1,500 of whom live in Mexico, once freely crossed.
The once-placid reservation feels like a "militarized zone," said Ned Norris Jr., the tribal chairman, who also says the tribe must cooperate to stem the cartels. "Drug smuggling is a problem we didn't create, but now we're having to deal with the consequences."
Many residents say they live in fear of the smugglers and hordes of migrants who lurk around their homes, and also of being subjected to a humiliating search by federal agents.
The elderly avoid the desert, even in the daytime, because they might stumble upon a cache of marijuana or drug "mules" hiding in desert washes until dark.
"We can't even go out to collect wood for the stove," said Verna Miguel, 63, who was traumatized three years ago when a group of migrants forced her to stop on a road, beat her and stole her vehicle.
"We've always picked saguaro fruits and cholla buds," Ms. Miguel said, using such desert products for consumption and rituals. "But now we don't dare do that."
Until recently, the reservation's international border was porous, defended by three strands of barbed wire. Over the last two years, it has been lined with metal posts and Normandy-style barriers to stop the trucks that used to barrel through and head for Phoenix.
Federal officials describe the rise in drug seizures on the reservation as a sign of growing success on what had long been a vulnerable section of border. Barriers and surveillance have forced most of the smugglers to enter on foot rather than in vehicles and spend hours or days sneaking through the reservation, making them more vulnerable to detection, said Agent Robert Gilbert, chief of the Tucson sector of the Border Patrol.
But the large busts, here and elsewhere on the border, are also a measure of the continued trade and profits reaped by the cartels.
"The cartels use the profit from marijuana to purchase cocaine in Colombia and Peru and the ingredients for meth and heroin from other regions," said Elizabeth W. Kempshall, special agent in charge of the Arizona office of the Drug Enforcement Administration. "So marijuana is the catalyst for the rest of the drug trade."
The drug smugglers, mainly working for the Sinaloa Cartel, officials said, place scouts for days at a time on mountainsides, with night-vision goggles to monitor movements of the Border Patrol. The scouts communicate with Mexican or Indian guides using cellphones or two-way radios with rolling codes that cannot be intercepted, said Sgt. David Cray of the tribal police force, which has spent major amounts of money on border issues. During the day, the scouts hide in caves or under camouflage.
The Border Patrol has its own spotters and trucks with infrared video cameras that detect heat miles away. The tribe has agreed to electronic surveillance towers that in coming years will make a "virtual fence" across their lands.
Many agents spend their nights "cutting for sign," a tracker's term, making slow drives on dirt roads in search of footprints.
One recent chilly night, a Border Patrol spotter detected eight white dots on his screen moving steadily north, not meandering the way cows or wild mules do. With a laser beam he fixed their coordinates at a spot five miles from his mountaintop post.
Two agents in four-wheel-drive vehicles set out over a rutted ranch track, then hiked through half a mile of mesquite, cholla and prickly pear to intercept the group. Six escaped, but two Mexican men were captured with seven burlap packs, each filled with 50 pounds of marijuana that sells wholesale for $500 or more per pound.
For the agents, it was a good night's work. "This is what we live for, stopping drugs," said an agent who hiked in shortly after the bust to help bring in the smugglers and the contraband.
But many tribal members see the federal presence as a mixed blessing at best.
Ofelia Rivas, 53, of Meneger's Dam Village is an Indian rights advocate and a rare border resident who agreed to speak to a reporter. She said that most families in border villages, including her own, had had a relative imprisoned for drug offenses, but that such individuals should not be blamed for the lack of legal jobs. Ms. Rivas has criticized tribal leaders for acquiescing to what she calls an oppressive federal occupation.
Federal law officials praise the tribe for its cooperation, and the Border Patrol has fielded community relations officers to minimize frictions.
Even Mr. Norris, the tribal chairman, said he had been stopped and questioned. "Quite frankly, the people are getting sick of it," he said of the heavy outside presence. But he added that the smuggling was beyond the tribe's ability to control.
"I hope in my lifetime we can go back to the way it used to be," Mr. Norris said, "where people could go and walk in the daylight on our own land."
We are careful not to duplicate the efforts of other organizations, and as a grassroots coalition of prisoners and social reformers, our resources (time and money) are limited. The vast expertise and scope of the various drug reform organizations will enable you to stay informed on the ever-changing, many-faceted aspects of the movement. Our colleagues in reform also give the latest drug war news. Please check their websites often.