146 



of the Nation. The estuarine zone, then, is nearly twice as densely 

 populated as the rest of the country, and supports only one-fourth 

 as much agriculture per unit area. 



The magnitude of population and agricultural development in the 

 estuarine zone is shown in table IV.3.1 by densities in terms of tidal 

 shoreline. The few estuarine areas in the Pacific Southwest show the 

 greatest shoreline development for both living and farming as shown 

 by population density of 3,980 persons per mile of tidal shoreline and 

 a farmland density of 4.9 acres per mile. The Middle Atlantic region, 

 in contrast, has a very high population density and a low farmland 

 density, showing how in this region the estuarine zone developed as 

 a center of population while agriculture developed elsewhere. 



The difference in estuarine land use development between these 

 two regions probably results from the difference in rainfall. The low 

 rainfall in the Pacific Southwest required the intensive use for farm- 

 ing of all land amenable to irrigation, of which a major part was 

 that near the mouths of the major rivers. The plentiful rainfall in 

 the Middle Atlantic region, however, permitted the use of much land 

 away from the estuarine zone for farming, so that the intensive 

 estuarine land use pattern of the Pacific Southwest did not develop. 



In those regions lying between Cape Hatteras and Canada, as well 

 as in the Pacific Southwest, over 90 percent of the population lives in 

 urban areas; over much of the Atlantic estuarine zone stretches the 

 great Northeastern megalopolis with population densities averaging 

 over 1,000 persons per square mile. The remainder of the estuarine zone 

 of the United States exhibits a pattern of major centers of population 

 clustered around natural harbors and separated by stretches of coast- 

 line which are either empty and inaccessible or beginning to be sprin- 

 kled with private residences and resort communities in the vicinities 

 of population centers. 



Agriculture in the estuarine zone itself tends to follow the crop pat- 

 terns typical of neighboring inland areas, although there are some 

 important crops which require special conditions of humidity or soil 

 dampness most easily found in the estuarine zone, if not directly 

 associated with estuarine waters themselves. Cranberries in New 

 Jersey and Massachusetts, rice in Texas and Louisiana, and sugarcane 

 in Hawaii, Louisiana, Florida, and Puerto Rico are examples. 



INDUSTRIAL DEVELOPMENT 



Table IV.3.2 gives a general picture of the extent of industrial de- 

 velopment in the estuarine zone. The coastal counties have within their 

 borders 40 percent of all manufacturing plants in the United States, 

 thus closely paralleling population concentration into the estuarine 

 zone. The mixture of manufacturing types in the estuarine zone is 

 the same as the national composition with only minor exceptions, such 

 as the concentration of the apparel manufacturing industry in the 



