The 55-car trains make the run between Washington and New York in approximately 124 hours.
Paul Esposito, Railex's senior vice president, said the demand for service had forced the company to expand some trains to more than 70 cars.
He said the company hauls more than 220 truckloads of produce across the county each week, saving an estimated 100,000 gallons of diesal fuel per train and lowering emissions by 85,000 metric tons per year.
The 64-foot Railex cars feature fresh air exchange, GPS tracking and temperature control technologies.
"We use Union Pacific cars that are only a few years old," said Esposito, "and the GPS system allows us to always know where they are."
Esposito said the company has been expanding rapidly and plans to open another facility in California within a year that will initially make shipments to Wallula but will ship directly from California to New York in the near future.
"For now we'll be utilizing the same commodity base," said Esposito, "but once we tap into California, we'll likely be expanding what goods we ship.""