What Coordinate System Should I Use?

Have you ever used a map to find your way somewhere?

Maps are great because they help us understand where things are in the world. But did you know that there are different ways to show locations on a map? That's where coordinate systems come in!

A coordinate system is like a special language that maps use to tell us where things are.

Just like how we use words and letters to communicate, coordinate systems use numbers and symbols to show locations on a map. However, it’s not quite that simple…

Have you ever looked at a map and noticed that the shape of things doesn't always look quite right? 

Maybe a state or country looks stretched out or squished. That's because when we make a map, we have to take a 3D object, like the Earth, and turn it into a 2D picture.

This is a tricky thing to do, and it's called projection (not the kind your ex was talking about). 

Different mapmakers use different projections to make their maps, and each projection has its own strengths and weaknesses.

Projections - Strengths and Weaknesses

One of the challenges of map projection is that it can distort the shape, area, and distance of things on a map.

For example, on some maps, Greenland looks bigger than Africa, even though Africa is actually many times larger! That's because the map projection used stretched out the polar regions more than the equator.

Another challenge is that different coordinate systems can also cause distortion. Depending on the coordinate system used, some maps might show a different shape or size for the same area on the Earth. For example, if you compare a map using one projection to a map using a different projection, you might notice that the shapes of some areas look different.

So, why do we use maps if they're not always perfectly accurate? Maps are still useful even with their imperfections. They help us understand the world around us and find our way. Plus, mapmakers are always working on improving their maps and making them more accurate.

How to Know What Coordinate System to Use

One popular coordinate system is called WGS84.

WGS84 is used all over the world, and it's especially good for showing locations that are far apart, like on a globe. It’s also the standard if you’re publishing to the web to make an interactive web map.

Another popular coordinate system is called NAD83. NAD83 is mostly used in North America, and it's good for showing locations that are closer together. 

NAD83 (which stands for North American Datum 1983) is a coordinate system that is widely used in North America, particularly in the United States. 

It is an updated version of an older coordinate system called NAD27, which was used from the 1920s until the 1980s. NAD83 is more accurate than NAD27 and takes into account changes in the Earth's surface over time.

One thing to keep in mind about NAD83 is that it is often used in conjunction with State Plane coordinate systems. State Plane coordinate systems are a way of dividing up the United States into smaller regions, each with its own unique coordinate system.

These coordinate systems are designed to minimize distortion and provide greater accuracy for local mapping projects.

There are over 120 different State Plane coordinate systems in use in the United States, each covering a specific region.

To find the specific coordinate system for your region, you can use a tool like the US National Geodetic Survey's State Plane Coordinate System Calculator. Simply click and drag to move the pin on the map, and the tool will tell you which coordinate system to use.

For example, if you live in Los Angeles County in California, you would use the California State Plane Coordinate System Zone 5 (CSPCS5), which is based on NAD83. This would give you more accurate results than using WGS84 or another coordinate system that is not specific to your region.

So how do you know which coordinate system to use?

Well, it depends on what you're trying to show on your map!

If you're making a map of the whole world, you'll want to use WGS84. But if you're making a map of just one country or city, you might want to use NAD83.