The distribution of moisture over the surface of the continent is effected in much the same way as is the distribution of heat. The Gulf Stream gives an abundant rainfall to the States about the Gulf of Mexico lying to the north of that basin; its effects on the rainfall are seen even as far north as the New England States, but they have little effect to the west of the Mississippi River. The high mountains of the Cordilleras cut off the Pacific winds from the centre of the continent, so that very little of the water which flows down to the Gulf of Mexico or to the Atlantic is derived from the Pacific. From the general conditions thus rudely outlined the following arrangement of climates arises. The northern half of the continent is more completely under the dominion of the Arctic Sea than any part of Europe or Asia; the only parts of it fit for the use of civilized man are the northern watershed of the St. Lawrence, the valley of Lake Winnipeg and the Saskatchewan, and the west-coast region as far north as Alaska. The rest of the northern part of the continent is practically barred out from the life of the race by the intensity of the winter cold, and by the brevity of the summer season. South of this domain of northern cold, North America divides itself, by its climate, soil, and topographical reliefs, into the following fairly distinct regions: (1) The eastern lowlands lying between the shore and the Appalachian range; these shade southwardly into (2) the lowlands of the Gulf States, which is the only part of North America in the immediate control of the Gulf Stream. These Gulf lowlands pass northwardly into (3) the great plain of the Mississippi Valley. Between these lowlands of the centre of the continent and the Atlantic sea-coast lie (4) the table-lands and mountains of the Appalachian system. West of the Mississippi Valley lie (5) the region of the Cordilleras of North America; and finally on the western shore we find (6) a narrow region of low mountains, forming a slender fringe of shorelands.