What Is a Map Key?


Sometimes called a legend, a map key is a table that explains what the symbols on a map mean. This helps the person reading the map understand where to find certain items. For example, a map of a mall may have symbols that reveal bathrooms, places to eat, elevators and guest services areas. A map of a city may have symbols for roads, parks, tourist attractions and public transportation stations.

More on Symbols 

While the person who creates the map can determine which symbols to use, there are some symbols that are universal. For example, a long blue line often indicates a river, while black lines represent roads. A black dot represents a city, while a star is a capital city. Green spaces often represent parks or forests. Airplanes represent airports, and a red cross is a hospital.

What Is a Map?

A map is a visual that represents a space. It can show a space as small as one room or as large as the entire world. It shows spatial relationships between its features, and it can show other information, such as climate, political boundaries, elevation, financial information and much more. Maps are created by cartographers. 

What Is Cartography? 

Cartography is the practice of designing maps. The practice combines art, science and technique. Cartography, or mapmaking, has been in practice since ancient times.

The Oldest Maps

The oldest map ever discovered was found in a cave in Lascaux, France, in 2000. It depicts the stars in the night sky carved into the cave wall. Scientists believe it dates back over 16,500 years to the Magdalenian Era. Other ancient cultures, including the Greeks, Romans, and Chinese also used maps.

Changes Through the Years  

While most modern maps are printed on paper, digital maps are becoming more popular. People can access these maps on computers, phones, tablets and even in car GPS systems. Even the way maps are made has changed over the years. The earliest cartographers used land surveying to create maps. Eventually, they began using aerial photography. Today, satellites are often used for cartography.  

Types of Maps

While there are many different types of maps, most can be divided into two categories: general purpose or thematic. General purpose maps are designed to show the exact locations of things, such as road maps, atlases, maps of buildings and wall maps.

Thematic maps are a bit more complicated. They provide general ideas about an area based on a central theme, such as the climate of a region, a state’s population, a country’s economy or a city’s voting habits. Thematic maps may use color patches, dots, an isopleth or choropleth.

Interesting Facts About Maps

While the north is usually featured at the top of maps, that hasn’t always been the case. Muslims once made maps with south at the top when Mecca was located south of their location. Many Europeans positioned east at the top.

Some governments around the world practice map censorship. For example, Russia requires that maps show Crimea as a part of Russia.

Bologna Ptolemy, the first printed atlas, sold for $3.12 million in 2007. The Library of Congress paid $10 million for the Universalis Cosmographia map that dates back to 1507. It’s believed this is the first map to use the name America.