THE ATLANTIC AND GULF COASTAL PLAIN.—This region is of comparatively recent origin, its elevation nowhere exceeds 500 feet, the rocks of which it is composed are weak and unconsolidated, and it is generally, though not always, covered with a deep and fertile soil. Its southern position, low relief, and proximity to the ocean have given it a climate, moist, warm, and on the whole equable. Only in Virginia and in Tennessee does the mean winter temperature fall below 40° F., while the mean summer temperature over the whole region ranges from F. to 83° F. The precipitation as far west as the ninety-third meridian is from 50 to 55 inches, except in South Carolina and Georgia, where it does not exceed 50 inches. Beyond the ninety-third meridian the rainfall rapidly diminishes in amount, and near the hundredth, that is in the west of the southern prairies, which for convenience are con sidered along with the Atlantic and Gulf Coastal Plain, it does not exceed 20 inches.
Throughout almost the whole of this region, as well as in parts of the Piedmont Plateau, the cultivation of the cotton plant is the chief pursuit of the agricultural population. Climatic conditions are of the utmost importance in bringing this about. The proximity of the Atlantic and the Gulf of Mexico prevents the great extremes of climate which are characteristic of continental masses, and ensures a sufficiently long growing season. The temperature increases until the maximum is reached in July, after which there is not only a somewhat lower temperature, but a greater diurnal range. In the spring the cyclonic disturbances, originating on the plains of Texas and moving in a north-easterly direction, cause an inflow of warm, moist air from the ocean. As the summer advances, the low-pressure area, developing over the continent, leads to a steady atmospheric inflow from the sea to the land and a heavier rainfall. In August, the land has cooled slightly, while the air temperature over the ocean is at its highest. The temperature gradient is therefore not so steep, and there is that decrease in precipitation, except along the coasts, which tends to check the growth of the cotton plant, and enables it to mature its seed. The region under consideration covers an area of about 600,000 square miles, but it must not be thought of as exclusively devoted to the cultivation of cotton. More than half of it is still forested, only about 60 per cent. is in farms, not more than 30 per cent. has been " improved,"
and the area under cotton, probably not more than 10 per cent. of the whole, is exceeded by that under maize within the same region.
The figures that appear on the next page indicate the nature of the change which has taken place in the location of the cotton fields within the last sixty years.
The great development within recent years of the cotton-growing area to the west of the Mississippi is due in part to the exhaustion of the soil to the east of it, largely as a result of the wasteful methods of ante-bellum cultivation, and in part to the greater facility with which the virgin lands of Texas can be brought under the plough.
Great although the production of raw cotton in the United States undoubtedly is, it has within recent years only met with difficulty the rapidly increasing demands made upon it by different parts of the world, and it seems unlikely that the future will see any great expansion of the cotton belt beyond its present limits. To the north of the thirty-seventh parallel the temperature is too uncertain, and to the west of the hundredth meridian the rainfall is too low, to afford much prospect of indefinite extension. On the other hand, only a small proportion of the land within the cotton growing area at present bears that crop, and it is believed that part of the remainder might be rendered productive by removing timber, by draining swamps, and by reclaiming impoverished land. But the most fertile areas have already been occupied, and it is probable that, only in exceptional cases, will the new lands,. added at considerable cost, fail to prove less remunerative. Influenced by considerations such as these, various members of the Agricultural Service of the United States have expressed the opinion that it is in the adoption of more intensive methods of cultivation that the best hopes of an increased output actually lie. It is said that one seldom comes across a really first-class field of cotton in the States ; and this indeed might be inferred from the fact that the average yield there is only about 190 lbs. per acre, while " on large tracts, carefully prepared, as much as 500 to 800 lbs. per acre are fre quently obtained." Various causes contribute to this discrepancy between the actual yield of the land and its potential capacity.