From the Puget Sound Business Journal:
Container terminals at the Port of Tacoma were nearly twice as busy as those in Seattle during 2015, according to statistics from the Pacific Maritime Association.
The statistics show that Port of Tacoma terminals handled the equivalent of 1.62 million 20-foot containers, a measurement called TEUs, during 2015. Terminals at the Port of Seattle handled 877,000 containers during the same period.
Seattle terminals have suffered from the temporary closure of Terminal 5 until it can be upgraded to handle larger ships, an action that moved some of the cargo to Tacoma.