What type of map has circles on it?

Circles on Maps: What Are They Telling You?

Maps. We all use them, but have you ever stopped to really look at one? I mean, beyond just figuring out how to get from point A to point B? Sometimes you’ll see circles sprinkled across a map, and those aren’t just decoration. They’re telling a story! But what story are they telling? Let’s dive in and decode those circular clues.

One of the most common types of maps you’ll see with circles is something called a graduated symbol map. Think of it like this: the bigger the circle, the bigger the something it represents. These maps, also known as proportional symbol maps or size theme maps, use different sized circles (or sometimes other shapes) to show you how much of something exists in a particular place. The size matters. It’s directly linked to the amount of stuff being shown.

For instance, imagine a map showing the populations of different cities. Los Angeles would get a huge circle, while a smaller town would get a much smaller one. It’s a super easy way to compare things visually. These maps are great for showing straight-up numbers, not percentages or anything fancy. We’re talking raw data, like city populations, how many times a certain event happened, or even how much stuff a factory churns out.

Now, within the graduated symbol family, there’s a special type called a proportional circle map. Here’s a little secret: it’s not just the radius of the circle that matters, it’s the area. Why? Because our brains are better at judging areas than just lines. So, mapmakers actually calculate the square root of the data to figure out how big to make each circle. Tricky, right?

I remember seeing one of these maps showing flood damage claims after a big storm. The circles really drove home just how much some areas were hit harder than others. These maps are perfect for showing a wide range of values, from tiny to enormous.

Then there are dot density maps. These don’t always use circles, but often do. Instead of size, it’s the number of circles (or dots) that matters. Each dot represents a specific amount of something. Maybe one dot equals 1,000 people. The dots are scattered randomly within a region, like a county or a state. The more dots crammed into an area, the more of that “something” there is.

Dot density maps are awesome for showing patterns. You can instantly see where things are clustered together. They’re great for mapping things like the number of farms in an area or where a particular group of people lives.

Now, let’s talk about isopleth maps. These are a bit different. They mostly use lines, but they’re still relevant. Isopleth maps show areas of equal value. Think of a weather map showing temperature. The lines connect all the points with the same temperature.

While they don’t directly use circles, sometimes you’ll see color bands representing different ranges. So, you might have a blue band for cold temperatures and a red band for hot ones. You could almost think of those bands as big, irregular circles representing a general temperature range.

Of course, circles can pop up on all sorts of other maps too, depending on what the mapmaker is trying to show. Thematic maps, in general, are all about highlighting a specific topic or idea.

So, next time you see a map with circles, here’s your cheat sheet for figuring out what it means:

Once you get the hang of it, decoding those circles becomes second nature. Happy mapping!