Latitude and Maps Many maps of Earth have a grid of lines indicating latitude and longitude in degrees. The horizontal grid lines indicate latitude. Anyone who can observe the pole star accurately can determine her latitude, and locate herself on a map somewhere on a line of that latitude. Latitude is a permanent standard for locating a precise position on Earth. Other scales of distance, such as feet, meters, miles, and kilometers are also very useful information on a map.
Small distances are difficult to measure by observing latitude.
For large distances, however, latitude observations greatly improve the accuracy of large maps built up from many small maps. Latitude observation becomes a significant practical skill for travellers and for administrators of large kingdoms. The kingdom of ancient Egypt existed in a narrow strip along the Nile River. Knowing latitude meant knowing where in Egypt one was. The vertical grid lines on a map indicate longitude.