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Thematic map

geography Maturity 7-9 Next article →

A thematic map is a special kind of map. Most maps are general reference maps. They show where things like roads, rivers, and buildings are located. A thematic map is different because it shows a specific subject or theme.

choropleth
choropleth

It helps us see patterns that are not naturally visible to our eyes. For example, you cannot see the temperature or the number of people in a city just by looking at the ground. Thematic maps use symbols to make these hidden details easy to see. They can show things from the natural world, like soil or climate. They can also show things from the human world, like public health or how people vote.

There are many different ways to build these maps. One popular way is called a choropleth map. This method uses different colors or shading to fill in specific regions.

choropleth
choropleth

For instance, a darker color might show a higher number of people. Another way is to use proportional symbol maps.

2016 US Presidential Election Pie Charts
2016 US Presidential Election Pie Charts

These maps use shapes like circles or squares at specific locations. The size of the shape tells you the amount of something, like a city's population. Some maps even use a technique called a cartogram.

PaullHennig2016WorldMap.OAha.CC-BY-4.0
PaullHennig2016WorldMap.OAha.CC-BY-4.0

A cartogram changes the actual size or shape of a country to match its data. This makes a place look much larger or smaller than it is on a normal map.

People have been making these maps for a long time. Many modern techniques were invented between the years 1700 and 1850. One early maker was the astronomer Edmond Halley.

Halley compass variations 1702
Halley compass variations 1702

In 1701, he published a chart showing lines of equal magnetic variation. This was likely one of the first isarithmic maps. Another famous example comes from a doctor named John Snow in 1854.

Snow-cholera-map-1
Snow-cholera-map-1

He mapped where people were dying from cholera in London. By looking at his map, he found a pattern near a specific water pump. This discovery helped stop the sickness from spreading.

History shows us many great thinkers used these tools. In 1826, Charles Dupin created the first known choropleth map. Later, Louis-Léger Vauthier used lines to show population density in Paris in 1874. Another master was Charles Joseph Minard.

Minard
Minard

He made a very famous map in 1869 about Napoleon's invasion of Russia. He combined maps with statistical charts to tell a story. These maps helped people understand big events through numbers and pictures. Every map maker used different strategies depending on the data they had.

Today, thematic maps are more popular than ever before. In the past, people had to draw them all by hand. Now, we have powerful technology to help us. Personal computers and the internet make it easier to collect data. We also use something called a Geographic Information System, or GIS.

FlowMap
FlowMap

This technology helps us see huge amounts of information at once. We can use digital data from national censuses to see how populations change. These maps help us answer important questions about our world. They allow us to compare how things change over many years.

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🖼️ Images & Media (11)
File:Minard.png
Minard.png
File:USDA Hardiness zone map.jpg
USDA Hardiness zone map.jpg
File:Halley compass variations 1702.jpg
Halley compass variations 1702.jpg
File:Snow-cholera-map-1.jpg
Snow-cholera-map-1.jpg
File:choropleth.gif
choropleth.gif
File:2016 US Presidential Election Pie Charts.png
2016 US Presidential Election Pie Charts.png
File:PaullHennig2016WorldMap.OAha.CC-BY-4.0.jpg
PaullHennig2016WorldMap.OAha.CC-BY-4.0.jpg
File:January 17 1982 500-Millibar Height Contours.png
January 17 1982 500-Millibar Height Contours.png
File:Geologic Map of Georgia.png
Geologic Map of Georgia.png
File:Dot Density.png
Dot Density.png
File:FlowMap.png
FlowMap.png
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