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 generally comes in three forms: containerized—cargo transported by container, bulk—cargo transported unpackaged, like grain or oil, and break bulk—cargo, such as a car or barrels, loaded individually, rather than in containers or in bulk.  Most non-bulk cargo is transported by intermodal container.  Such containers can be transferred between different modes of transportation, for example, from ship to rail, without removing the cargo from the container.

Port districts and port development authorities are prohibited from using port funds to purchase fully automated marine container cargo handling equipment until December 31, 2031.  Container cargo handling equipment is fully automated if it is remotely operated or remotely monitored.  Port districts may use funds to purchase human-operated zero, or near zero, emission equipment and the infrastructure to support the equipment.

The expiration date of December 31, 2031, is removed. Port districts and port development authorities are prohibited from using port funds to purchase fully automated marine container cargo handling equipment after December 31, 2031.