Port districts are a type of special purpose district that can be created with voter approval. Port districts can include harbors and marine transport, but can also be formed in inland areas without major navigable waterways and can include airports, railroads, and other facilities. Port districts are funded by property taxes, services fees, lease fees, and bonds. Port districts may also receive funding from the federal government and from the state. Currently, there are 75 port districts in Washington.
A port development authority can be created by a port district, or jointly by two port districts if both are located in counties with more than 800,000 people, to manage the maritime activities of the port district or districts. The Port of Seattle and the Port of Tacoma have formed a port development authority, The Northwest Seaport Alliance.
Marine cargo can come in multiple forms. Examples include cargo transported by container (containerized cargo); cargo transported unpackaged, like grain or oil (bulk cargo); cargo, such as barrels, that is loaded individually, rather than in containers or in bulk (break bulk cargo); and cars or trucks (roll-in/roll-off cargo). Most non-bulk cargo is transported by intermodal container. Such containers can be efficiently transferred between different modes of transportation; for example, containers can be moved from ship to rail without removing the cargo from the container.
Until December 31, 2031, port districts and port development authorities may purchase zero and near zero emissions cargo handling equipment and infrastructure, but may not purchase fully automated marine container cargo handling equipment. Fully automated equipment is that which is remotely operated or monitored, with or without human control.