Western Hemisphere

The Western Hemisphere, also Western hemisphere ["Oxford Dictionary of English", 2nd ed., rev. 2006. London, UK: Oxford University Press, p. 2001.] or western hemisphere, [ [http://www.m-w.com/dictionary/western%20hemisphere "Merriam Webster's Online Dictionary"] (based on Collegiate vol., 11th ed.) 2006. Springfield, MA: Merriam-Webster, Inc.] 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), the other half being the eastern hemisphere. [" [http://www.britannica.com/oscar/print?articleId=275388&fullArticle=true&tocId=203675 Latitude and longitude] " "Encyclopædia Britannica". 2006. Chicago: Encyclopædia Britannica, Inc.] It is also used 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, it is sometimes referred to as the American hemisphere.Olson, Judy M. " [http://www.gis.psu.edu/projection/chapter4.html Projecting the hemisphere] ", ch. 4 from " [http://www.gis.psu.edu/projection/ 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" is sometimes used as an equivalent for the geopolitical construct, the "Western World", which typically includes the Americas, Europe and Australia.

Only approximately 15 % of world's population lives in the western hemisphere.

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, ["Western Hemisphere". "Merriam-Webster's Geographical Dictionary," 3rd ed. 2001. Springfield, MA: Merriam-Webster, Inc., p. 1294.] 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 the Prime Meridian, in order from north to south:
*United Kingdom
*France
*Spain
*Algeria
*Mali
*Burkina Faso
*Togo
*Ghana

Below is a list of the countries which are in both the Western and Eastern hemispheres along the 180th meridian, in order from north to south:
*Russia
*United States
*Kiribati
*Tuvalu
*Wallis and Futuna (France)
*Fiji

Countries in the Western Hemisphere but not in the Americas

The following countries lie outside the Americas (or New World) yet are in part or entirely within the Western Hemisphere.
*Algeria
*American Samoa (United States)
*Burkina Faso
*Cape Verde
*Cook Islands (New Zealand)
*Faeroe Islands (Denmark)
*Fiji
*France
*French Polynesia (France)
*Gambia
*Ghana
*Guinea
*Guinea-Bissau
*Iceland
*Ireland
*Ivory Coast
*Kiribati
*Liberia
*Mali
*Mauritania
*Morocco
*Niue (New Zealand)
*Pitcairn Island (United Kingdom)
*Portugal
*Russia
*Samoa
*Senegal
*Sierra Leone
*Spain
*Togo
*Tokelau (New Zealand)
*Tonga
*Tuvalu
*United Kingdom
*Wallis and Futuna (France)
*Western Sahara (Morocco)

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