Rail intermodal traffic fell 4.4% for the week ended Saturday compared with the same week a year ago, the Association of American Railroads said.
Containers plunged 4.9% to 175,768 units year-to-year, while trailers fell 2.5% to 48,597 units, AAR said in its weekly rail traffic report.
Overall rail carload traffic inched up 0.3% to 335,865 carloads, the group said.
Railroad volume is considered an important economic indicator. Intermodal traffic, which tends to be higher-valued merchandise than bulk commodities, uses trains for the long haul and trucks for the shorter distance at either end of the trip.