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From navigating a cross-country road trip (or just finding the nearest coffee shop), to analyzing election results, maps play a huge role in how we interpret the world! Today, we're going to talk about the differences between reference maps and thematic maps, take a closer look at how projections play a part in how we perceive maps, and discuss the role of the cartographer (or map maker) in all of this. Maps are incredibly powerful tools and play a crucial role in how we understand the world, but they are also made by people, so it is our job to think critically about how these stories are being presented to us.

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From espressos and cappuccinos to cafe au lait and plain black, there’s a coffee out there for almost everyone.  We can even visualize it on a map like this, where the color of each country represents how much coffee they drink per person. So much of the world loves coffee!

And I agree. For me there’s nothing better than a morning latte. But for coffee to get to my favorite coffee shop, it first has to make it through a pretty long journey.  We won’t go bananas and get into the full geographic story of coffee, but in 2020 coffee is mostly grown in the “Bean Belt,” which is -- oh I’ll just show you.

My favorite coffee shop is much closer though -- over on Elm Street. From my house, take a left at the end of the street, go to the bottom of the hill, and take another left, past the house where the grey cat is always sitting on the porch.

A few blocks later, there’s that beautiful garden along the side of the yellow house. Walk past there, take a right at the next corner, and the café is straight ahead. At least, that’s the mental map I follow every morning.

We all have maps we use as tools to help us navigate or better understand wherever we are. And in geography, we use maps to study, analyze, and interpret spaces, places, and human-environment interactions. We use maps in all shapes and sizes to tell the story of the Earth.  They’re colorful, detailed, and lots of times, difficult to fold!

I’m Alizé Carrère and this is Crash Course Geography. INTRO.

 Map Basics (1:17)

Formally, a map is a symbolic representation of space, which is all the facts and features about a particular spot. Maps can be used to compare spaces (and places) on Earth and beyond or shape our sense of reality.

Like, when you search “map” on the internet, this world map is one of the first things that comes up.  A world map is a type of reference map. Reference maps can show mountains, cities, oceans, elevation -- everything people might say "yep, that's there."

But the Earth is almost spheroid, or a slightly wonky sphere. So this reference map also has to do the hard work of representing our three-dimensional world in just two-dimensions.  Like taking the 3D Earth and squishing it onto paper or a flat computer screen. Imagine doing that with a tomato. What a mess.

 Thematic Maps (1:57)

For cartographers, or map-makers, it’s a challenge with many solutions. They need to pick which data they want to focus on, and the type of map they pick often depends on what story they want to tell. For example, we might want to use these three maps to talk about the number of people in each country around the world.

They’re thematic maps, which visualize data about a particular topic across a space. Instead of being something we’d use to navigate on a cross-country road trip, thematic maps tackle abstract ideas, like average rainfall or voting results by political party, and explore how frequency, concentration and patterns are distributed across a space. For example, these three thematic maps are designed to visualize population data.

 Choropleth Map (2:32)

First, we have a choropleth map, which shows how a theme like population changes over a particular space using different colors or shadings of colors. This is shown in the map’s key or legend which unlocks the map and shows us how to get into the map and interpret it. Notice how the key moves from light purple to deep violet depending on the population density -- the number of people per some amount of area.

When we look at this, we can tell pretty quickly the population density in most of South America is quite low. Except for the northern tip of the continent, there are between 0 and 25 people per square kilometer. But wait.

As of 2020, Sao Paulo in Brazil is actually one of the 20 most populated cities in the world. So nowhere in Brazil has more than 25 people per square kilometer? Nowhere?

Choropleth maps are useful because they quickly tell us which countries or regions belong in the same category overall. With a glance we see Australia and Canada and Russia and most of South America all fit in the same population density category.

But by shading a whole area, choropleth maps can make things look a little too simple, which can be a problem.  They imply there’s an evenness to whatever they're showing -- even though there are parts of Sao Paulo with wayyy more than 25 people per square kilometer and other parts of Brazil with absolutely no people.

 Dot Density Map (3:38)

Let’s try a different thematic map that will let us be a bit more specific. A dot density map uses a dot to represent a key feature or attribute.

The cartographer decided that each dot on this map represents 100,000 people. So while the choropleth map showed the general population spread out over an entire country, this dot density map has more granularity and shows where within a country people live. More or less.

We can see the coasts of Brazil have more dots -- and more people. But take a look at the Sahara or Siberia. No one lives exactly where those dots are!

The cartographer also decided where to place each dot to summarize population data. But it’s a simplification that could mislead someone if they're not paying close attention like we are! A dot doesn’t necessarily mean 100,000 people live exactly there.

Cartographers are always trying to make maps easily readable, but all the choices they make can influence accuracy. For example, if we changed how our dot density map is projected, or how the 3D Earth was flattened into 2D, the size and shape of the continents would shift, and so would the dots. We might accidentally imply some areas have a closer population density while others are more spread out.

 Cartogram (4:41)

Our last thematic map for today is a cartogram map, which uses size to compare data -- like population density -- regardless of the actual space these regions take up on the Earth's surface. With this map, the really populous countries are giant, while ones with smaller populations are tiny. But it looks weird to us or at least me, because we're used to maps that tell us something about the physical space that countries and continents take up.

India has a much bigger population, but in real life Australia is a muuuuch larger country -- it’s about 7.7 million square kilometers while India is less than half the size with 3.28 million square kilometers.

 Map Projections and Choices (5:14)

Each of these thematic maps uses a different lens to tell the story of the world population. Different maps represent data in different ways.  And the more information a geographer has, the better interpretations they can make about a particular story -- like human population.

Of course, there are many, many more stories to tell, so there are many, many more maps. And by helping us visualize data across space, maps actually shape our perception of reality too!  Alright, that sounds a bit melodramatic. But every map was made by a person making choices. And those choices (however thoughtful, or simple, or unintentionally biased) have an impact on how we imagine the world.

Like, we’re so used to seeing north at the top of a map and south at the bottom. But why? Well, that's a choice made by a cartographer.

Other cartographers tried something different with a Fuller projection that unfolds the. Earth and ends up with a completely different orientation without distorting anything. This map doesn’t have Greenland at the very top of the map, like we might be used to.

There’s more than one way to represent Earth. By thinking about what a map was supposed to be used for, we can spot these obvious or not-so-obvious choices made by cartographers.

For centuries humans have been using maps as navigational tools to help us understand our physical surroundings.  Stick charts like these are made of fibers from coconuts and shells that were developed by mariners from the Marshall Islands. These charts weren’t used to navigate exactly the same way that we use maps today. They weren’t carried along in the boats, but studied and memorized to get a better idea of the islands, waves, winds, and currents in the Pacific Ocean.

Stick charts were personal -- mariners had their own stick charts that they used to get back to places they’d visited. Kinda like my mental map to my favorite coffee shop. These charts were someone’s own perception of the space in their individual world.

Maps can also be used politically, and the choices about where to draw borders on a map are giving spaces a national identity. For example, there's a dispute over territory in Antarctica and some nearby islands that’s currently on pause thanks to a 1959 treaty. Originally the 12 countries whose scientists had been conducting research on the continent signed and agreed that no activities taking place would mean they’d claimed the territory.

But in the 1960s, despite the treaty, Argentina published maps claiming territory in Antarctica. So anyone who uses those maps would perceive this land as part of Argentina. But where to draw borders isn’t the only political decision a cartographer can make.

Let’s go to the Thought Bubble. Let’s say it’s the 1950s and we’re U. S. cartographers working on a new world map.  The Cold War between the United States and the Soviet Union is nearing its height, and the tension can influence our mapmaking decisions. First, we have to choose a kind of projection, like the Mercator projection. First made in 1569 by the Flemish cartographer Gerardus Mercator, this type of map basically turns the spheroid Earth into a cylinder.

The Mercator projection shows the lines of longitude, or meridians, as equally spaced and parallel vertical lines traversing pole to pole. The lines of latitude, or parallels, are also parallel lines on this map, but get spaced farther apart as we move north or south of the equator. (On a globe, meridians aren’t equally spaced, but curve together at the poles.)

With this layout, the scale gets distorted and areas farther away from the equator appear bigger than they really are. Like, look at Greenland.  It’s essentially the same size as all of Africa! It’s not that this representation is wrong -- every map choice comes with flaws. But by choosing a Mercator projection, the USSR looks large and menacing.

That's just the beginning, so we sketch out country borders. And now it’s time to add color. As US based cartographers, red is our first choice for the USSR.  In the West, “Red” or the “Red Scare” are synonymous with fear of communism. Representing a major foe to the United States in red sends an immediate message to the viewer. But for further effect, let’s add the hammer and sickle -- weapons reminiscent of the scythe of Death and the symbol of the Soviet era, which evoked fear in Americans.

As you can see, with just a few mapmaking choices, we can actually help stir up some major nationalistic emotion. Thanks Thought Bubble! Though the Cold War is over, our maps still reflect nationalistic fervor in more modern times.

 Data Visualization and Choices (8:47)

We like to think of data and numbers as being objective, but how data is displayed on maps can affect what people believe about the world. Like these two maps both show the Hispanic population in Florida based on the 2000 Census. They look like very different maps, but it’s actually the same data!

Maps can even be used to tell stories about societal problems. On this map, major chemical accidents, environmental disasters, freak weather patterns, and deforestation are all included with different symbols. So looking at this map might make you feel like the Earth experienced great environmental stress in the 1980s and 1990s.  And that’s a choice the cartographer made.

Maps can make strong arguments because they pull a lot of visual information together, which can increase our awareness about certain issues -- or greatly skew our understanding of the world. Maps are powerful tools, and they’ll be a crucial part of our journey through geography.

But we can't rely on just one map. Every map is telling a particular story with how it’s visualizing data, and it’s our job to think critically about what’s being presented to us. Many maps and borders represent modern geopolitical divisions that have often been decided without the consultation, permission, or recognition of the land's original inhabitants.

Many geographical place names also don't reflect the Indigenous or Aboriginal peoples languages. So we at Crash Course want to acknowledge these peoples’ traditional and ongoing relationship with that land and all the physical and human geographical elements of it. We encourage you to learn about the history of the place you call home through resources like and by engaging with your local Indigenous and Aboriginal nations through the websites and resources they provide.

Thanks for watching this episode of Crash Course Geography which was made with the help of all these nice people. If you would like to help keep all Crash Course free for everyone, forever, please consider joining our community on Patreon.