BAYONNE, NJ—The battle of America's two coasts is beginning to make some serious waves. For the first time since World War II, the East Coast surpassed the West in container traffic growth, according to a new report, "North American Port Analysis: Preparing for the First Post-Panamax Decade" from Colliers International.

Upon completion in 2015, the expansion of the Panama Canal will accommodate vessels capable of carrying up to 12,500 containers, will alter global trade routes, and is already promoting the advancement of the science of logistics. According to the report, Eastern ports saw traffic grow by 5.5% in the first quarter of 2012 over the same quarter in 2011, as compared with 3% in the western ports.

By 2015, Baltimore, New Jersey and Norfolk will all be ready to handle larger ships, bigger cranes and deeper channel depth—and Eastern traffic growth will accelerate further, says K.C. Conway, executive managing director of market analytics at Colliers and the author of the study.