What term describes the direction of north established by vertical grid lines on a map?

The term that describes the direction of north established by the vertical grid lines on a map is "grid north." This concept is critical for navigation and map reading, as grid north refers specifically to the direction along the grid lines of a map. These vertical lines represent the structure of the grid system used for coordinates, which helps users orient themselves when reading the map.

Grid north may differ from true north (the direction along the Earth's rotational axis) and magnetic north (the direction a magnetic compass points). Understanding grid north is essential for accurately interpreting a map and navigating effectively in various terrains. It ensures that map users can align their maps correctly with the physical world, which is vital for achieving their navigation goals.