However, the data also show that growth was held back by a mere 0.9 percent rise in inbound traffic at the Northwest Seaport Alliance ports - Seattle and Tacoma - as well as a 0.6 percent dip at Oakland, according to the PMSA, which released the data Oct. 20.
In the Canadian province of British Columbia, the Vancouver and Prince Rupert seaports combined to post a healthy 9.5 percent gain of plus-16,904 TEUs in August, PMSA data show. Meanwhile, on the Pacific Coast of Mexico, the Manzanillo and Lazaro Cardenas ports saw a 7.8 percent -- 12,145 TEU -- increase.
On the export loaded TEU side, the big five US West Coast ports handled 48,092 fewer outbound TEUs this August than they had a year earlier, statistics show, a decline of 10.1 percent. Of the five, only the Port of Los Angeles saw export growth, with its numbers rising four percent, or 6,192 TEUs.
The two British Columbia ports saw their outbound trades fall by 7.16 percent, or negative-7,568 TEUs, while the two Mexican ports saw a 1.3 percent (1,151 TEUs) rise in August exports, according to the PMSA.
By declared value, West Coast ports held a 50.1 percent share of containerized imports at all US mainland ports in August, up from 49.2 percent in July and slightly up from their 49.6 percent share in August 2016, data show.
However, when it comes to declared weight of the containerized exports, US West Coast ports saw a 6.2 percent drop in tonnage from August 2016, according to the PMSA, and their share of containerized export tonnage dropped in August to 39.9 percent, down from a 41.6 percent share in August 2016.
By declared value, USWC ports had a 34.3 percent share of containerized exports from mainland ports in August, down from a 35.1 percent share a year ago.
Looking at the Transpacific containerized trade, USWC ports’ share of the declared weight of the contents of containerized imports arriving at mainland ports from East Asia rose slightly in August to 59.3 percent, but was still lower than the 60.3 percent share the port held in August 2016, PMSA data show.