What do lines of longitude measure?

• A. Distance east and west of the Prime Meridian
• B. Distance north and south of the equator
• C. Elevation above sea level
• D. Distance between poles

Answer: (A)

Lines of longitude tell you how far east or west a place is from the Prime Meridian, the line at 0° longitude that runs from the North Pole to the South Pole. These meridians are measured in degrees east or west, up to 180°. Longitude forms the vertical grid of the globe and pairs with latitude, which measures north–south position relative to the equator. Elevation is about height above sea level, not angular position, and the distance between poles isn’t what longitude measures. So longitude is all about east–west location relative to the Prime Meridian.