thumb|Map of the Western Hemisphere
The Western Hemisphere is the half of the planet Earth that lies west of the Prime Meridian and east of the 180th meridian. The other half is called the Eastern Hemisphere. In the United States, the term "Western Hemisphere" is often used as a metonym for the Americas, even though geographically, the hemisphere also includes parts of other continents.
Geography
thumb|The Western Hemisphere in a photo taken from [[Deep Space Climate Observatory in June 2022]]
The Western Hemisphere comprises the Americas, except some of the Aleutian Islands to the southwest of the Alaskan mainland; the westernmost parts of Europe and Africa, both mainland and islands; the extreme eastern tip of the Russian mainland and islands (North Asia); many territories in Oceania; and a large part of Antarctica.
The center of the Western Hemisphere on the surface of the Earth is in the Pacific Ocean, at the intersection of the 90th meridian west and the Equator, among the Galápagos Islands. The nearest land is Genovesa Island at .
The highest mountain in the Western Hemisphere is Aconcagua, in the Andes of Argentina, at .
thumb|270px|Countries in the Western Hemisphere
The tallest freestanding structure in the Western Hemisphere is the CN Tower, in Toronto, at . The tallest building in the Western Hemisphere is One World Trade Center, in New York City, at .
Other definitions
In an attempt to match the Western Hemisphere more closely with the Americas, some sources use the 20th meridian west and the diametrically opposed 160th meridian east to define the hemisphere.