Organic oranges from Mexico. Their next stop: Los Angeles. (Kassie Bracken/The New York Times)

Organic oranges from Mexico. Their next stop: Los Angeles. (Kassie Bracken/The New York Times)

Listening to salsa music and talking on his cell phone, Juan de Dios Camacho kills time as he sits and waits to get into the United States. At this point he has completed two-thirds of a trek that can take up to 18 hours, from Guasave, Sinaloa, to the Mariposa Land Port of Entry in Nogales, Mexico.

Distance-wise, he is less than one mile from Arizona. Time-wise, however, he will have to wait at least an hour to reach the port of entry and up to four hours for his truck’s inspection to be complete.

“One just sits here and waits and waits,” said a bored de Dios Camacho, who has driven a truck for 23 years and whose face bears tan lines from his sunglasses and long hours on the road. A card-size image of Jesus fastened behind him on the back of the cab accompanies him on every trip.

January marks the start of the peak season for winter produce to cross from Mexico into the United States. For the next three months, up to 1,300 trucks a day will enter the States from Nogales through a 33-year-old complex designed to process only 400 trucks per day, according to a binational report.

More than half the produce transported from Mexico to the United States enters through four commercial lanes of the Mariposa port of entry, making it the largest produce port along the border.

In the last year and a half, U.S. Customs and Border Protection has stepped up searches for narcotics and other illegal cargo, which delays truck drivers and can cause fruit and vegetables to deteriorate on their way to warehouses north of the border, according to the produce industry.

Because of the tightening of border security in California and Texas, more drug smugglers are attempting to send narcotics over the border through Arizona, said Allison Moore, a spokeswoman for the Fresh Produce Association of the Americas, a group of Mexican industry growers. For this reason, she said, security and inspections have increased in the border city of Nogales, Ariz.

Truck drivers and produce warehouse managers say that each time a trailer-truck’s doors are opened for inspection, or produce is removed from refrigeration — or, worse, vegetables or fruit are left out in the open — growers fetch less in the marketplace for these commodities because the shelf life is shorter.

Trailers transporting produce are equipped with cooling systems that are set at specific temperatures to maintain the quality of fruit and vegetables. But when officers open the doors or unload cargo to perform inspections, they compromise these temperatures, which dramatically reduces the freshness of the load.

“The shelf life of a tomato is 21 days, but if the cold chain is broken, it goes down to 15,” said Leonardo Tarriba, general manager of Farmer’s Best, a large company that grows tomatoes, cucumbers, squash and bell peppers in the northern Mexico states of Sonora and Sinaloa. “That’s less days we have to move our product and less days our customers have to sell the product.”

U.S. Customs and Border Protection officials agreed that delays have increased as the search for narcotics has intensified. But Armando Goncalvez, program manager for trade at the Tucson Field Office of Customs and Border Protection, said that in some cases, importers do have an alternative to waiting at the border. They can ask to have produce inspected at their U.S. warehouses.

Goncalvez said that did cost the importer more because officers must escort the truck from the port of entry to the warehouse where they will conduct the inspection. In addition, requests for such inspections are granted only for highly perishable items.

Truck drivers say they wait in holding rooms at the U.S. port of entry while inspectors search the cargo. The length of the inspection is out of the driver’s power, but de Dios Camacho says that warehouse managers at his destinations often blame him if the quality of the produce has been compromised.

“They just screw us up,” de Dios Camacho lamented while waiting in a line of trucks with engines humming, knowing that his green bean load was going to be searched.

But delays also originate in Mexico, where the produce is often inspected before it reaches the U.S. border. An estimated $52 million a year is lost when produce deteriorates and loses market value because of delays at inspection checkpoints in Mexico, according to an industry study.

Although a new checkpoint was opened last April in Querobabi, Sonora, the inspection station operates only intermittently, according to a report from the Mexico National Defense Secretariat. And drivers say the delay there can add up to eight hours per trip.

The checkpoints in Mexico are part of a comprehensive campaign to fight drug trafficking and are in compliance with Mexico’s Federal Law of Firearms and Explosives, said Lt. Col. Francisco Enriquez, deputy director of public affairs for the country’s National Defense Secretariat.

At the port of entry, the inspection process begins when a customs officer receives a broker’s report including information about the driver, the load, and both the importer and the exporter. The truck operator then drives the load through radiation detectors and proceeds to a screening area, where drug-sniffing dogs walk around the carrier. Finally, the truck is weighed; officers either wave the driver into Arizona or through another inspection area, where the entire trailer may be unloaded.

Agents from the U.S. Food and Drug Administration, the U.S. Department of Transportation and the Arizona Motor Vehicle Division may also inspect the truck.

When U.S. customs officers find drugs hidden in a shipment of produce, the legitimate cargo can be delayed for some hours, though it is usually eventually released to the importer.

Narcotics are often found between pallets or along boxes containing produce. In some cases, inspectors have found drugs hidden among the produce. If illegal cargo is found in a produce shipment, an investigation begins at the port of entry, said Brian Levin, chief Customs and Border Protection Officer and public affairs liaison at the Tucson Field Office.

To avoid this further delay, many companies have established procedures to keep drivers from accepting drugs along the northern route, which starts near the fields of Mexico and ends in an Arizona warehouse.

Some companies track their drivers with logbooks that require time and location entries. Others use GPS or satellite systems.

For example, Farmer’s Best placed GPS in its fleet of trucks and installed surveillance systems in warehouses in Mexico and the United States. When a truck deviates from its planned route, the company’s customs brokers send a report to U.S. Customs and Border Protection about the incident, leaving it up to the federal agency to investigate.

Even with these safeguards, produce company managers say, drug smugglers still make advances to the carriers traveling north.

Drug dealers threaten to harm drivers and their families, Tarriba, of Farmer’s Best, said. They know “where they live, where their kids go to school, and on top of that, they offer them money. So, drivers or employees at that level accept the deal. They have no choice.”

If drugs are found in a produce load, the port closes for hours at a time, industry experts said.

With the clock ticking and produce companies growing more frustrated about losing profits, the industry argues that the infrastructure at the Mariposa port is simply inefficient.

“My complaint about what’s going on is that U.S. Customs probably doesn’t have the facilities nor the resources, or the personnel, to take care of the task,” Tarriba said. “It’s a big task.”

But the waiting game may have an end date: spring 2014.

The Mariposa port of entry will be expanding because of a $213 million investment, financed largely by the American Recovery and Reinvestment Act of 2009. According to the U.S. General Services Administration, by 2014, the port will have eight commercial lanes, 56 docks for commercial cargo, 24 inspection areas and five exit booths.

While the port’s modernization gives truck drivers like de Dios Camacho hope that they will spend less time lingering at the border crossing, some doubt that the changes will solve the problem entirely, because some of the delays begin as far south as 50 miles from the port.

In the meantime, as Jesus watches and the salsa plays, de Dios Camacho leans in his seat and contemplates the road ahead of him.

“I hope the new port makes the crossing more agile,” de Dios Camacho said. “The two, three hours one spends in line, one could instead be resting.”

An earlier version of this article gave the wrong number of commercial lanes at the Mariposa port of entry. There are four commercial lanes, not three.