Final answer:
North and South America are in the Western Hemisphere based on their position relative to the Prime Meridian at 0 degrees longitude.
Step-by-step explanation:
North and South America are in the Western Hemisphere according to the Prime Meridian. The Prime Meridian is an imaginary line that is set at 0 degrees longitude and serves as a global reference point for dividing the Earth into the Eastern and Western Hemispheres.
The continents located to the west of the Prime Meridian, which runs through the Royal Observatory in Greenwich, England, are part of the Western Hemisphere. This includes both North and South America. Meridians to the east of the Prime Meridian are marked as east longitude, while those to the west are marked as west longitude. Meridians, or lines of longitude, are used alongside parallels, or lines of latitude, to define precise geographical locations on Earth.