The thieves target mostly shipments of food and beverages, which are easy to sell on the black market and hard to trace. Some end up on the shelves of small grocery stores. Others go to huge distribution warehouses like the one authorities raided in August in North Hollywood, Calif. It was filled with stolen steaks, shrimp, energy drinks, ice cream and other frozen foods.

Last year, carriers reported nearly 1,200 cargo thefts of all kinds nationwide, about the same as the previous year, according to CargoNet, a division of Verisk Crime Analytics, which estimated losses that year at nearly $216 million. Since many thefts go unreported, the real figure is almost certainly far higher.

The most common crime is still the "straight theft" of trailers left unattended in parking lots or at truck stops. But CargoNet says the new trucking scams are growing at a rapid 6 percent each quarter. Of the average three to five truckloads stolen each day in the United States, at least one involves what are known in the industry as fraudulent or fictitious pickups.

The thefts emerged three or four years ago and are now "the latest, greatest thing" for organized groups seeking to steal freight, said J.J. Coughlin, vice president for law enforcement services at LoJack SCI, a supply chain protection company.

LoJack examined 947 cargo thefts last year and identified 45 of them as fictitious pickups. So far this year, the number of fictitious pickups has probably already doubled, Coughlin said. The average loss last year was more than $170,000 per incident.

Although cargo thieves prey on companies across the nation, the hot spots are places with shipping ports or rail hubs. California leads the nation. Large numbers of thefts have also been reported in Texas, Florida, New Jersey, Michigan, Illinois, Georgia, Pennsylvania and Tennessee.

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