We call a harbour or airport a mainport if:
- there is intercontinental transportation
- there is modal split: changes between different means of transport
- there are large transport streams
- there is a favourable location:
* economic location
* geographical location
The man in charge of a harbor is called a harbor master. They are responsible for overseeing the operations, safety, and security of the harbor, as well as managing incoming and outgoing vessels.
Portland International Airport is the closest commercial airport but there is a small plane airport called Mount Saint Helens Aero Ranch Airport in Cougar, Washington.
The biggest airport in Spain is Adolfo Suárez Madrid-Barajas Airport, located in Madrid. It is the busiest airport in Spain in terms of passenger traffic and serves as a major hub for international flights.
Jomo Kenyatta International Airport is the main international airport in Kenya, located in Nairobi.
The harbor of Rio de Janeiro, also known as Guanabara Bay, is a natural bay located in the city of Rio de Janeiro, Brazil. It is famous for its stunning natural beauty and iconic landmarks like Sugarloaf Mountain and Christ the Redeemer statue. The harbor is also an important transportation hub and a popular spot for sailing and water activities.
The airport code for Friday Harbor Airport is FRD.
The airport code for Old Harbor Airport is OLH.
The airport code for Hancock County-Bar Harbor Airport is BHB.
Phoenix - Sky Harbor International Airport, AZ, USA (PHX)
Jakarta is the Mainport of Indonesia
The airport code for Kenmore Air Harbor is KEH.
The airport code for Christiansted Harbor Seaplane Base is SSB.
Phoenix Sky Harbor International Airport was created in 1928.
The airport code for Roche Harbor Seaplane Base is RCE.
The airport code for Friday Harbor Seaplane Base is FBS.
The airport code for Ketchikan Harbor Seaplane Base is WFB.
The airport code for Coffs Harbour Airport is CFS.