Western Hemisphere

The Western Hemisphere is the half of Earth that lies west of the Prime Meridian, extending from 0° longitude to 180° west. It includes North and South America, parts of western Europe and Africa, and large areas of the Atlantic and Pacific Oceans.

Understanding the Western Hemisphere helps explain how longitude divides the world, how time zones differ across continents, and how places relate to one another in global geography.

What Is the Western Hemisphere?

The Western Hemisphere includes all locations on Earth that are positioned west of the Prime Meridian (0° longitude). Any place with a west (W) longitude value falls within the Western Hemisphere.

Together with the Eastern Hemisphere, it forms Earth’s primary east–west geographic division.

Where Is the Western Hemisphere on Earth?

The Western Hemisphere stretches from the Prime Meridian westward to the 180° meridian. It covers:

North America
South America
Parts of western Europe
Parts of western Africa
Large portions of the Atlantic and Pacific Oceans

Because the Prime Meridian passes through Greenwich in London, regions immediately west of Europe and Africa fall within the Western Hemisphere.

Which Major Cities Are in the Western Hemisphere?

Many well-known cities are located in the Western Hemisphere, including:

New York
Toronto
Los Angeles
Mexico City
São Paulo
Buenos Aires
Lima
Havana

These cities lie west of the Prime Meridian and experience time zones that are generally behind Greenwich Mean Time (GMT).

How the Western Hemisphere Is Different from the Eastern Hemisphere

The Western and Eastern Hemispheres are divided by longitude rather than latitude. This division is primarily used for navigation, mapping, and timekeeping.

When comparing the two hemispheres:

The Western Hemisphere contains the Americas
It includes fewer continents than the Eastern Hemisphere
It spans a wide range of climates, from polar regions to tropical zones

Western Hemisphere and Time Zones

Longitude determines local time, which is why the Western Hemisphere is closely associated with time zones that are behind GMT.

As you move westward from the Prime Meridian, local time decreases. This relationship explains why cities in the Western Hemisphere experience daylight later than those in the Eastern Hemisphere.

How the Western Hemisphere Relates to Antipodes

Every location in the Western Hemisphere has an antipode located in the Eastern Hemisphere.

Because much of the Western Hemisphere is ocean, many antipodes of Western Hemisphere cities fall in the Indian Ocean, Pacific Ocean, or on land in Asia or Australia. This uneven land distribution explains why true land-to-land antipodal pairs are uncommon.

How to Tell If a Place Is in the Western Hemisphere

A location is in the Western Hemisphere if:

Its longitude is marked west (W) of the Prime Meridian
Its longitude value is between 0° and 180° west

For example:

New York: 74.0060° W
Los Angeles: 118.2437° W

Both cities are clearly located in the Western Hemisphere.

Western Hemisphere Maps and Visualisation

Maps of the Western Hemisphere often highlight the Prime Meridian, major longitude lines, and continental outlines. Viewing a place within the Western Hemisphere provides context — showing how far west it lies and how it connects to global geography, time zones, and antipodal relationships.