What is Map Reading?

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Map reading (also sometimes written as map-reading) is the act of interpreting or understanding the geographic information portrayed on a map.  

Through map reading, the reader should be able to develop a mental map of the real-world information by processing the symbolized information shown on the map.  

To do this, the reader will need to derive essential information presented by the map such as distance, direction, natural and man-made features, and topographical features.

Step by Step Instructions to Learn How to Read a Map

To understand how to read a map, we are going to look at different maps including this example of a USGS topo map. USGS topo maps are maps created for the entire United States that show topography (hence the name) along with information about roads, water features, , and grid lines.

The USGS topo map we will look at is the 1:24,000 scale Half-Dome map which covers a portion of Yosemite National Park.

USGS 1:24,000 scale topo map for Half-Dome, 2018.
USGS 1:24,000 scale topo map for Half-Dome, 2018.

Now that we have our example map, let’s get started on learning how to read this USGS topo map.

Map Title

Just like the title of a book, the map title will give you a clue as to what the intent of the map is. Map titles can be found in many places on a map. The font size of a map title is typically very large as to draw the viewer’s attention.

In our example map, the map title is found at the top of the map.

Title section for the 2018 USGS Topo Map of Half-Dome.  Map: USGS, public domain.
Title section for the 2018 USGS Topo Map of Half-Dome. Map: USGS, public domain.

The title section for this type of map from the USGS is a little different than most maps you will find. The title is actually split across the top of the page. The title section to the left of the image is the title for the map series: US Topo.

US Topo is a map series that the USGS creates showing topography in sections known as quadrangles for the entire United States. To the right of the above image is the title for this particular quadrangle: Half-Dome. Next is the state the quadrangle covers: California. Last is the map scale for the quadrangle: 1:24,000.

On other maps, the title of the map will be more obvious and descriptively titled. Take, for example. this 1777 map of New York and New Jersey. The title section of the map has been enlarged for view ability. The title is quite description. By reading the title, the reader can understand the geographic focus of the map as well as well the source information is from that was used to create the map.

A map of the provinces of New-York and New Jersey, 1777.  The map title has been enlarged for this article.  Map: Library of Congress.
A map of the provinces of New-York and New Jersey, 1777. The map title has been enlarged for this article. Map: Library of Congress.

Locator Map

A locator map is a smaller map that shows the relative location of the geographic area mapped to a larger area.

For example, this map of Texas has a locator map, also sometimes referred to as a inset map, that shows the relative location of Texas (shaded red) to the rest of the continent United States.

Map of Texas with a locator map showing the relative location of Texas within the continental United States.
Map of Texas with a locator map showing the relative location of Texas within the continental United States.

Referring back to our example Half-Dome topo map, this locator map shows the relative location of the quadrangle (red square) to the rest of the state of California.

Underneath the locator map is an index map which can be found on maps that are part of a map series or an atlas. The point of the index map is to show the location and names of the surrounding quadrangles to the Half-Dome map. This is useful if you are looking for the topo map that is just out of the range of the current topo map you have.

Locator map and index map on a USGS Topo map.
Locator map and index map on a USGS Topo map.

Understanding the Symbols on the Map

Since maps are representations of the real world, cartographers will use symbols and colors to indicate to the reader what they are mapping.

What the symbols on the map mean are defined in what’s known as the map legend or the map key.

The point of a map legend is to describe what all symbols on the map mean. Maps with a complete map legend or key can be used without the need for additional interpretation guides.

The map below shows the General Plan land use zones for the City of Santa Clarita in California, the map in the lower right corner lets the reader understand the meaning of the different colored areas.

By matching the color to the match legend, users can understand that zones shaded red are industrial, blue shades are industrial, and yellows are non-urban residential.

Map showing the General Plan for the City of Santa Clarita, California.
Map showing the General Plan for the City of Santa Clarita, California.

The US Topo maps can contain a lot of symbology that isn’t defined on each individual quadrangle. If you look for the map legend on our example Half-Dome quadrangle map, you will notice the legend is very sparse:

Map legend on the US Topo map for Half-Dome.  Map: USGS.
Map legend on the US Topo map for Half-Dome. Map: USGS.

If you look at a small section of the Half-Dome map, you will see that there are a lot of symbols that are not included in the very small legend on the USGS map. There simply isn’t enough room to include all the symbology on these very detailed maps.

To understand what those symbols mean, you would need to reference the USGS Topographic Symbols guide to look them up.

Section of the Half-Dome US Topo map.  Map: USGS
Section of the Half-Dome US Topo map. Map: USGS

Some symbols are meant to be intuitive. For example, the green symbol with the picnic table lets you immediately understand this point on the map is a rest area where you could stop to eat food. The light brown symbol with the hiker lets you know that path is a hiking trail.

There are other symbols that are harder to understand which is where the USGS Topographic Symbols guide comes in handy. For example, we can see areas that look like this:

USGS Topo Map symbology.  Map: USGS.
USGS Topo Map symbology. Map: USGS.

So what do the blue symbols mean? If we look in the symbol guide, we learn what those symbols mean by looking for a matching symbol:

Submerged areas and bogs symbology, USGS topo maps.  Source: USGS.
Submerged areas and bogs symbology, USGS topo maps. Source: USGS.

Map Orientation

Understanding cardinal directions is one important aspect of reading a map. Which way is north, south, west, or east?

To show direction, maps will contain a north arrow. A lot of maps are oriented so that north is towards the top of the map. When a map is oriented with the map towards the north, the north arrow will indicate that North is directly up:

A compass rose showing just the cardinal points of north, south, east, and west.
A compass rose showing just the cardinal points of north, south, east, and west. Adapted from Brosen~commonswiki, CC BY 2.5, Medawiki Commons

In the Half-Dome map example, the USGS puts more technical information to show both the direction of geographic north (GN) and magnetic north (MN):

North arrow on a USGS Topo map.
North arrow on a USGS Topo map.

Not all maps are oriented with north at the top of the map. For example, maps in the Middle Ages were frequently oriented with east towards the top.

For a more current example, let’s take a look at the city of Santa Monica in California. This beach town sits along the coast of the Pacific Ocean.

For readability and aesthetics, cartographers at the city rotate maps 46 degrees so that the beach side lines up along the bottom of the page. In this map of the city streets, notice that the north arrow in the lower left hand corner is tilted to show the direct of due north.

Related: To North Arrow or Not to North Arrow

Street map for the City of Santa Monica showing a map rotation of 48 degrees.
Street map for the City of Santa Monica showing a map rotation of 48 degrees.

Understanding Map Scale

Map scale is a way for cartographers to let the reader know how to translates distance on the map to distance on the ground. Map scale is a expression of the ratio of a distance on the map to the distance in the real world.

For example, the Half-Dome map has a scale of 1:24,000. This ratio means that every one unit on the map is equal to 24,000 of the same units on the ground. This type of map scale is known as Representative Fraction (RF).

Therefore, 1 inch on the map is equal to 24,000 inches on the ground.

Map scale can also be expressed as a ratio of one type of unit to another type of unit. You might see a map scale expressed as 1″ = 100′. That means that one inch on the map is equal to 100 feet in the real world. This type of map scape is known as a Verbal Scale.

A third option for map scale is to show the relationship of the map to the real world as a bar scale. A bar scale is essentially a ruler on the map. Distance on the map is expressed as a graphic and the corresponding distance is noted on the bar scale.

This example from the Half-Dome map shows both a RF and has a few map scales:

Map scale on a USGS Topo map.
Map scale on a USGS Topo map.

You can learn more about map scale by reading the Map Scale article or by watching this video: Understanding Map Scale: Large Scale Versus Small Scale Maps

Map Metadata

The last important piece of information to understand about map reading is the metadata.

Metadata is data about the map. Typical pieces of metadata that you might find on a map are the name of the cartographer, the date the map was created, the source and dates of the data used to create the map, the map projection and datum used, and any disclaimers the creator of the map wants you to know about.

This is the metadata found on the Half-Dome USGS Topo map. The metadata lets you see how old the various datasets that the USGS used to create the Topo map are.

Metadata on a USGS Topo map.
Metadata on a USGS Topo map.

The metadata for the City of Santa Clarita’s General Plan map contains similar information about data sources, disclaimers, who created the map, and a link to the original file used to create the map.

Metadata for the General Plan map, City of Santa Clarita.
Metadata for the General Plan map, City of Santa Clarita.

Learn more: How to Read a Map

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