Latitude and Longitude Lines
When viewing a map, latitude lines run horizontally. Latitude lines are parallel lines and they are equaled distant from each other. Each degree of latitude is about 69 miles (111 km) apart; there is a slight variation because the earth is not a perfect sphere. Degrees latitude are numbered from 0° to 90° north and south. At Zero degrees you have the equator; this imaginary line divides our planet into the northern and southern hemispheres. At 90° north you have the North Pole and 90° south you have the South Pole.
The longitude lines are vertical lines also known as meridians. They come together at the poles and are widest at the equator (about 69 miles or 111 km apart). Zero degrees longitude is located at Greenwich, England (0°). The degrees continue 180° east and 180° west where they get together and form the International Date Line in the Pacific Ocean.
How Latitude and Longitude Work Together
To accurately locate points on the earth's surface, degrees longitude and latitude have been separated into minutes (') and seconds ("). There are 60 minutes in each degree. Each minute is divided into 60 seconds. Seconds can be then divided into tenths, hundredths, or even thousandths. For example, St Lucia lies between 60° 53' and 61° 05' West longitude and 13°43' and 14°05' North latitude.