Western Hemisphere

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The geographical western hemisphere of Earth, highlighted in yellow.

Western hemisphere

The Western Hemisphere, also Western hemisphere^[1] or western hemisphere,^[2] is a geographical term for the half of the Earth that lies west of the Prime Meridian (which crosses Greenwich in London, England, United Kingdom) and east of the International Date Line.^[3] It is also used, mainly by Americans, to specifically refer to the Americas (or the New World) and adjacent waters, while excluding other territories that lie geographically in the hemisphere (parts of Africa, Europe, Antarctica, and Asia). Thus this is sometimes referred to as the American hemisphere, despite the fact that it is by no means a hemisphere.^[4] Western hemisphere is sometimes used as an equivalent for the geopolitical construct, the Western World, which typically includes America and Europe.

Overview

Any definition of eastern and western hemispheres, however, requires the selection of an arbitrary meridian and a corresponding meridian on the other side of the Earth. The Prime Meridian at 0° longitude is typically used, which runs through Greenwich; this is used to define the International Date Line (or End Meridian) on the other side of the Earth at 180° longitude. In its proper geographic sense, the western hemisphere includes not only the Americas, but the western portions of Europe and Africa, the easternmost tip of Russia, numerous territories in Oceania, and a portion of Antarctica while excluding some of the Aleutian Islands to the southwest of the Alaskan mainland. Often, the meridians of 20° W and the diametrically opposed 160° E are used,^[4]^[5] which excludes the European and African mainlands but also excludes a small portion of northeast Greenland and includes more of eastern Russia and Oceania (e.g., New Zealand).

The two major regions of Antarctica are named after their positions mainly within a single hemisphere; West Antarctica is named for the Western Hemisphere.

Countries in both hemispheres

Below is a list of the countries which are in both the Western and Eastern hemispheres on either the Prime Meridian or opposite the prime meridian (180 degrees from it):

United Kingdom (England only), Europe
France, Europe
Spain, Europe
Algeria, Africa
Mali, Africa
Burkina Faso, Africa
Togo, Africa
Ghana, Africa
Russia
United States

Sources

^ Oxford Dictionary of English, 2nd ed., rev. 2006. London, UK: Oxford University Press, p. 2001.
^ Merriam Webster's Online Dictionary (based on Collegiate vol., 11th ed.) 2006. Springfield, MA: Merriam-Webster, Inc.
^ "Latitude and longitude" Encyclopædia Britannica. 2006. Chicago: Encyclopædia Britannica, Inc.
^ ^a ^b Olson, Judy M. "Projecting the hemisphere", ch. 4 from Matching the map projection to the need; Robinson, Arthur H. & Snyder, John P., eds. 1997. Bethesda, MD: Cartography and Geographic Information Society, American Congress on Surveying and Mapping.
^ "Western Hemisphere". Merriam-Webster's Geographical Dictionary, 3rd ed. 2001. Springfield, MA: Merriam-Webster, Inc., p. 1294.