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
it is one of the 7 natural wonders of the world
That point is in southeastern Arizona, about 30 miles southwest of Globe, 54 miles north of the center of Tucson, and 66 miles southeast of Sky Harbor airport in Phoenix.
Barajas Airport in Madrid is the largest airport in the country.
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.
Narita Airport (60 KM) from the city to the airport in Japan.
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.
The airport code for Roche Harbor Seaplane Base is RCE.
Phoenix Sky Harbor International Airport was created in 1928.
The airport code for Ketchikan Harbor Seaplane Base is WFB.
The airport code for Friday Harbor Seaplane Base is FBS.
The airport code for Marsh Harbour Airport is MHH.