Which lines on a map run vertically, indicating distances east and west?

The correct choice is identified as longitude, which refers to the imaginary lines that run from the North Pole to the South Pole. These lines are essential for determining the distances east and west of the Prime Meridian, which is located at 0 degrees longitude.

Longitude lines, in contrast to latitude lines, provide a framework for understanding global positioning along the east-west axis. This is critical for navigation, cartography, and understanding global time zones, as each degree of longitude typically represents about 69 miles (111 kilometers) at the equator. As you move towards the poles, this distance between lines of longitude decreases due to the curvature of the Earth.

In terms of context, latitude, which is also mentioned in the choices, runs horizontally and indicates distances north and south of the equator. Parallels are another term used to describe lines of latitude rather than longitude, while equinox refers to an astronomical event rather than a cartographic concept. Understanding the distinction between these terms is fundamental in geography and helps in comprehending how maps are structured.