As for the two ports, Long Beach and Los Angeles, they are next to each other and combined I believe become the busiest port in the country. All the stuff from China comes in RIGHT HERE.
The Port of Los Angeles is America's busiest port with record volumes of cargo moving through the 7500-acre harbor. Its strong performance is attributed to a solid U.S. economy and the recovering Asian economies with a renewed manufacturing demand for American exports.
The Port itself is a major reason for the remarkable cargo volumes. Its world-class facilities and infrastructure maximize the one-stop shopping concept of cargo transportation and delivery favored by most shipping lines. Ocean carriers can send the majority of their West Coast cargo to Los Angeles with full confidence in the Port's modern cargo terminals and efficient train/truck intermodal network.
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So, LA claims to be #1 in container traffic in the country without counting it's competive next door neighbor, Long Beach. Together, I do believe that they are number 1 in the world.