Intermodal traffic rose 9.2% last week compared with a year ago, the Association of American Railroads reported.
Traffic totaled 222,742 units, led by a 10.1% gain in containers to 190,140 units. Trailers rose 4.4% to 32,602 units.
U.S. railroads originated 291,147 carloads for the week ended Saturday, up 4.7%, AAR said in its weekly report.
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.