An Introduction to the USA: Hotel Reservations are Next!
49 states in the United States (all except Hawaii)
lie on the North American continent. 48 of these
(all except Alaska) are contiguous and form the
continental United States.
The U.S. shares borders with Canada and Mexico.
At the western half the northern boundary is
exactly at 49æ N (apart from Alaska being more
north and Vancouver Island, Canada reaching more
south). At the eastern half the northern boundary
is more south, except for Lake of the Woods, the
most northerly part of the U.S. apart from Alaska.
Area
The U.S. is the world's third largest country after
Russia and Canada with an area roughly:
- half the size of Russia or
- three-tenths the size of Africa
- half the size of South America
- slightly larger than Brazil or China
- two and a half times the size of Western
Europe
Physical Geography
Its geography varies across its immense area. Within the contential U.S.,
eight distinct physiographic divisions exist, though each is composed of yet
small physiographic subdivisions. These major divisions are the:
- Laurentian Highlands - part of the Canadian shield that extends into
the northern United States Great Lakes area.
- Atlantic Plain - the coastal regions of the eastern and southern parts
includes the continental shelf, the Atlantic Coast and the Gulf Coast.
- Appalachian Highlands - lying on the eastern side of the United States,
it includes the Appalachian Mountains, Adirondacks and New England
province.
- Interior Plains - part of the interior contentintal United States, it
includes much of what is called the Great Plains.
- Interior Highlands - also part of the interior contentintal United
States, this division includes the Ozark Plateau.
- Rocky Mountain System - one branch of the Cordellian system lying far
inland in the western states.
- Intermontane Plateaus - a system of plateaus, basins and gorges which
includes the Grand Canyon.
- Pacific Mountain System - the coastal mountain ranges and features in
the west coast of the United States.
The Atlantic coast of the United States is, with minor exceptions, low.
Here, lie the Atlantic Plain and Appalachian Highlands. The Appalachian
Highland owes its oblique northeast-southwest trend to crustal deformations
which in very early geological time gave a beginning to what later came to
be the Appalachian mountain system. This system had its climax of
deformation so long ago (probably in Permian time) that it has since then
been very generally reduced to moderate or low relief. It owes its present
day altitude either to renewed elevations along the earlier lines or to the
survival of the most resistant rocks as residual mountains. The oblique
trend of this coast would be even more pronounced but for a comparatively
modern crustal movement, causing a depression in the northeast resulting in
an encroachment of the sea upon the land. Additionally, the southeastern
section has undergone an elevation resulting in the advance of the land upon
the sea.
While the east coast is relatively low, the Pacific coast is, with few
exceptions, hilly or mountainous. This coast has been defined chiefly by
geologically recent crustal deformations, and hence still preserves a
greater relief than that of the Atlantic.
The low Atlantic coast and the hilly or mountainous Pacific coast foreshadow
the leading features in the distribution of mountains within the United
States. The east coast Appalachian system, originally forest covered, is
relatively low and narrow and is bordered on the southeast and south by an
important coastal plain. The Cordilleran System on the western side of the
continent is lofty, broad and complicated having two branches, the Rocky
Mountain System and the Pacific Mountain System. In between these, lie the
Intermontaine Plateaus. Heavy forests cover the northwest coast, but
elsewhere trees are found only on the higher ranges below the Alpine region.
The intermontane valleys, plateaus and basins range from treeless to desert
with the very arid region being in the southwest.
The numerous rivers that drain the Atlantic slope of the Appalachians are
comparatively short while those that drain the Pacific slope include only
three:
- the Columbia - its mouth being located in Oregon.
- the Sacramento - its mouth being located in northern California.
- the Colorado - its mouth being located in Mexico ( the Gulf of
California ).
Both the Columbia and Colorado rise far inland near the easternmost members
of the Cordilleran system, and flow through plateaus and intermont basins to
the ocean.
The Laurentian Highlands, the Interior Plains and the Interior Highlands lie
between the two coasts, stretching from the Gulf of Mexico northward, far
beyond the national boundary, to the Arctic Ocean. The central plains are
divided by a hardly perceptible height of land into a Canadian and a United
States portion. It is from the United States side, that the great
Mississippi system discharges southward to the Gulf of Mexico. The upper
Mississippi and some of the Ohio basin is the semi-arid prairie region, with
trees originally only along the watercourses. The uplands towards the
Appalachians were included in the great eastern forested area, while the
western part of the plains has so dry a climate that its native plant life
is scanty, and in the south it is practically barren.
Elevation extremes:
- lowest point: Death Valley, Inyo County, California -86 m
- highest point: Mount McKinley, Denali Borough, Alaska) 6,194 m
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