The geographical western hemisphere of Earth highlighted in yellow. Western hemisphere

The Western Hemisphere also Western hemisphere1 or western hemisphere2 is a geographical term for the half of the Earth that lies west of the Prime Meridian (which crosses Greenwich London United Kingdom) the other half being the eastern hemisphere.3 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 Western Hemisphere (parts of Africa Europe Antarctica and Asia); thus it is sometimes referred to as the American hemisphere.4

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. Sometimes the meridians of 20 W and the diametrically opposed 160 E are used45 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.

The population of the Western Hemisphere exceeds 1 billion however the Americas does not. Countries common to 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 Netherlands (because of the islands Saba Bonaire and St. Eustatius; they lie in the Antilles. The "continental" Netherlands lies entirely on the eastern hemisphere.) France Spain Algeria Mali Burkina Faso Togo

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) Nations in the Western Hemisphere but not in the Americas

The following nations 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) Faroe Islands (Denmark) Fiji France (Metropolitan area) French Polynesia Wallis and Futuna Gambia Ghana Guinea Guinea-Bissau Iceland Ireland Ivory Coast Kiribati Liberia Mali Mauritania Morocco Western Sahara Niue (New Zealand) Portugal Samoa Senegal Sierra Leone Spain Togo Tokelau (New Zealand) Tonga Tuvalu United Kingdom Gibraltar Guernsey Isle of Man Jersey Pitcairn Islands Saint Helena Ascension and Tristan da Cunha 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" Encyclopdia Britannica. 2006. Chicago: Encyclopdia 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. v d eHemispheres of the Earth Northern hemisphere Southern hemisphere Eastern hemisphere Western hemisphere Land hemisphere Water hemisphere

Coordinates: 0N 90W / 0N 90W / 0; -90