The Western Hemisphere or western hemisphere is mainly used as a geographical term for the half of the Earth that lies west of the IERS Reference Meridian (which crosses Greenwich, London, United Kingdom) and east of the Antimeridian, the other half being called the Eastern Hemisphere.
In this sense, the Western Hemisphere consists of the Americas, the western portions of Europe and Africa, the extreme eastern 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.
The term is often used in political rhetoric to refer to only North and South America (or the New World) and adjacent islands; however, the Western Hemisphere technically includes all of the aforementioned territories.
In an effort to define the Western Hemisphere as the parts of the world which are not part of the Old World, there also exist projections which use the 20th meridian west and the diametrically opposed 160th meridian east to define the hemisphere. This projection excludes the European and African mainlands and a small portion of northeast Greenland, but includes more of eastern Russia and Oceania (e.g., New Zealand).
The population of the geographical Western Hemisphere exceeds 1 billion.
Countries in both hemispheres
Below is a list of the countries which are in both the Western and Eastern hemispheres on the IERS Reference Meridian, in order from north to south:
- United Kingdom
- Denmark (Because of Greenland. Mainland Denmark lies entirely in the eastern hemisphere.)
- Norway (Because of Jan Mayen. Mainland Norway lies entirely in the eastern hemisphere.)
- Netherlands (Because of the islands Saba, Bonaire and St. Eustatius; they lie in the Antilles. The "continental" Netherlands lies entirely on the eastern hemisphere.)
- Burkina Faso
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:
Nations in the Western Hemisphere but not in the Americas
The following nations lie outside the Americas yet are in part or entirely within the Western Hemisphere.
- American Samoa (United States)
- Burkina Faso
- Cape Verde
- Cook Islands (New Zealand)
- Faroe Islands (Denmark)
- France (Metropolitan area)
- Greenland (Denmark) (note: geographically a part of North America, but politically a part of Europe)
- Ivory Coast
- Niue (New Zealand)
- Sierra Leone
- Tokelau (New Zealand)
- United Kingdom
- Oxford Dictionary of English (2nd ed.), London, UK: Oxford University Press, 2006, p. 2001.
- "Western Hemisphere", Merriam Webster's Online Dictionary (based on Collegiate vol., 11th ed.), Springfield, MA: Merriam-Webster, 2006
- Olson, Judy M (1997), "Projecting the hemisphere", in Robinson, Arthur H; Snyder, John P, Matching the map projection to the need, Bethesda, MD: Cartography and Geographic Information Society, American Congress on Surveying and Mapping.
- "Western Hemisphere", Merriam-Webster's Geographical Dictionary (3rd ed.), Springfield, MA: Merriam-Webster, 2001, p. 1294.