Forming a Grid

As mentioned earlier, longitude lines (meridians) are also used to pinpoint locations on a map or globe. Don’t forget that the main longitude line, the prime meridian, serves as a starting point for numbering degrees east and west. Also, the main latitude line, the equator, serves as a starting point for numbering degrees north and south.

When latitude and longitude lines cross, they form a set of intersecting lines known as a grid. Using the grid of crisscrossing latitude and longitude lines, it is possible to determine a location’s coordinates, or its location measured by latitude and longitude.