The Port of Seattle is a port district that runs Seattle's seaport and airport. Its creation was approved by the voters of King County, Washington, on September 5, 1911, authorized by the Port District Act. It is run by a five-member commission. The commissioners' terms run four years. In 2005, the Port of Seattle was the 5th busiest port in North America by twenty-foot equivalent units (TEU) of container ship traffic and the 46th busiest in the world.Among its facilities are the Seattle-Tacoma International Airport in SeaTac, Washington; the Shilshole Bay Marina; the Maritime Industrial Center and Fishermen's Terminal on Salmon Bay; cargo terminals and a grain elevator on Smith Cove; and numerous cargo terminals on Elliott Bay, Harbor Island, and the Duwamish Waterway. The Port of Seattle also controls recreational and commercial moorage facilities and two cruise ship terminals.

Although the Port has done considerable good work, it has not been without controversy. Perhaps the longest-running battle was over the third runway for Sea-Tac, which is now nearing completion and expected to become operational next year.There has been a surge in scandals and criticism during the past year or so. Among them are a quarter-million dollar severance package offered to the Port's former chief executive Mic Dinsmore, lax accounting practices found by state audits, and the discovery of pornographic and racist e-mails being exchanged by about a third of the Port's police force.