Longitude lines measure distance from which line?

• A. Prime Meridian
• B. Equator
• C. International Date Line
• D. Tropic of Cancer

Answer: (A)

Longitude lines measure distance east or west from the Prime Meridian, the reference 0° line that runs from the North Pole to the South Pole through Greenwich, England. These meridians stretch from pole to pole and get used to define how far east or west a location sits. The Equator is the 0° latitude line and marks distance north or south, not east or west. The Tropic of Cancer is another latitude line, about 23.5° north. The International Date Line sits near 180° longitude and marks a change of calendar date, but it’s not the starting point for measuring longitude.