IV-306 



and the terrain presented few obstacles. Connecting links were 

 needed between the coastal trade centers and the hinterlands, and 

 the level land available along the coasts, bays and rivers was the 

 natural location for railroads and highways for both engineering 

 and economic reasons. Airports also require large tracts of level 

 land, and a waterside location affords the benefits of unobstructed 

 and unpopulated approach zones. This concentration in coastal and 

 estuarine centers has continued as these areas have maintained 

 their growth and thereby further stimulated the maximum utilization 

 and exapnsion of transport facilities. 



Airborne commerce has experienced considerable growth. Some 

 statistics are available to relate it to estuarine locations. 

 Figure IV. 4. 14 gives some historical data on airborne import and 

 export commerce by coastal Customs Districts. Airport location on 

 or near an expanse of water is desirable because it affords un- 

 obstructed approaches and reduces noise problems. Airports are 

 presently located in estuarine areas in Boston, New York (both 

 Kennedy and La Guardia), Washington, Norfolk, San Diego, San 

 Francisco and Oakland. 



A further element which will almost certainly affect the estuarine 

 zone is the development of new ports. For example, if the proposed 

 free port in Maine becomes a reality there will be a rapid prolifera- 

 tion of all types of commercial transportation to service that port 



