UNITED STATES OF AMERICA, a Federal republic, composed of 48 States, the District of Columbia, the District of Alaska, the territories of Hawaii and Porto Rico, the Philippine Islands, Guam, Tutuila, the Panama Canal Zone, and the Virgin Islands; chiefly occupying the temperate portions of North America from lat. 24° 20' to 49° N., and lon. 66° 48' to 124° 32' W.
Boundary.—The United States is bounded on the N. by British North America, the boundary line running through the Strait of Juan de Fuca to the S. of Vancouver's Island, but to the N. of the island of San Juan, striking the mainland at the 49th parallel and run ning along that parallel to the Lake of the Woods, and thence by a devious route through the Great Lakes and along the Laurentian water-shed to the St. John's and St. Croix rivers and Fundy Bay. The land boundary is a clearing 30 feet wide, with iron mile posts 4 feet high painted white. The E. and W. boundaries are formed by the Atlantic and Pacific Oceans respectively, the S. boundary by the Gulf of Mexico, the Rio Grande del Norte up to the 32d parallel, and a broken line drawn between the 31st and 33d parallels to the Pacific separat ing the United States from Mexico. These boundaries do not include Alaska. The ocean shore lines are as follows: North Atlantic coast, including bays, islands, etc., 6,150 miles; South Atlantic coast, 6,209; Mexican Gulf coast, 5,744; Pacific coast, 3,251—total, 21,354. The land, lake, and river boundary toward Canada is 3,700 miles, and the similar one toward Mexico, 2,105 miles; making the total ocean, land, lake, and river boundary, 11,075 miles. Excluding Alaska the greatest Continental extent E. and W. is 3,100 miles and N. and S., 1,780 miles.
Area.—The tables shown on pages 81 and 82 give the area of the continental territory by States and Territories.
Topography.—The two great mountain systems of the United States are the Ap palachians and the Rocky Mountains. The former extend from the mouth of the St. Lawrence to the mouth of the Missis sippi—a distance of 1,300 miles—and at the S. bend inland, leaving the wide and rich seaboard of Virginia, the Carolinas, Georgia, Alabama, and Florida. This maritime region includes all the older States, and its inhabitants still amount to one-third of the whole. As far S. as the Hudson river it is hilly; thence, as far as the Alleghenies extend, its surface is divided between a plain and a mountain slope, the base of which appears to have been the shore of an ancient sea. The most fertile part of this slope is between Long Island and the Potomac. The coast to the Mississippi is sandy throughout; from Long Island to North Carolina it is marshy only close to the sea, but farther S. the seaward half of the plain is covered with swamps. The Appalach ians form the watershed between the rivers draining into the Atlantic and the tributaries to the Mississippi, though some of the former may be said to rise on the inland side of the mountains, and to force a passage through them to the sea. The principal rivers falling into
the Atlantic are the Penobscot, Kenne bec, Merrimac, Connecticut, Hudson, Delaware, Susquehanna, Potomac, Rap pahannock, James, Roanoke, Pedee, San tee, Savannah, and Altamaha. The Chat tahoochee and the Flint river joining form the Appalachicola; the Alabama and Tombigbee, the Mobile; these drain into the Gulf of Mexico E. of the Mississippi.
The great central plains and prairies between the Appalachians and the Rocky Mountains are drained almost entirely by the Mississippi and its affluents, chief of which are the Ohio, Tennessee, Mis souri, Arkansas, and Red river. The only other river of great importance flowing into the Gulf of Mexico is the great boundary river, the Rio Grande del Norte. The streams flowing N. are trifling, the principal being the Red river of the North, which flows into Lake Winnipeg. Almost the whole of the Mississippi basin consists of open, roll ing prairies, while, on the other hand, almost all the country between the Appa lachians and the Atlantic was originally more or less thickly wooded. Between the Rocky Mountains and the Pacific Alps, called Sierra Nevada, in California and Cascade Range farther N., lies a rainless region, mostly S. of lat. 45° N., with an average elevation of 5,000 feet above the ocean, great part of it com municating, not with the sea, but drain ing into salt lakes and marshes. Except where irrigated, this plateau is utterly unproductive. To the N. it is drained by the Columbia, with its tributary the Snake river, which forces its way through the Sierras to the Pacific; while in the S. portion the Colorado and its affluents, after flowing through frightful canons 3,000 to 5,000 feet below the sur face of the plateau for some 600 miles, forms a delta at the head of the Gulf of California. The Great Cation of the Colorado is more than 300 miles long. Between the Sierras and the ocean stretches the comparatively narrow but rich and beautiful sea-coast known as the Pacific Slope, drained by the Co lumbia, the Klamath, the Sacramento, and the San Joaquin, along with nu merous smaller streams. The "Great Divide," or watershed, is in Montana and Wyoming, whence flow the Missouri, Co lumbia, and Colorado. In this wild region Congress set apart in February, 1872, the Yellowstone National Park, a tract 62 by 54 miles in extent (3,312 sq. miles) in the N. W. of Wyoming. The region, while mostly unfit for agriculture and mining, contains more natural mar vels than can be found elsewhere. There are hot springs with their basins in crusted with calcareous spar, steam jets, geysers, mud volcanoes, waterfalls, caves with stalactites and stalagmites, eroded columns, statues, castles, cathedrals, etc., and a large lake swarming with fish. The valley of the Upper Yellowstone abounds in these wonders. Further de tails of the topography of the country will be found in the articles on the sev eral States and Territories.