My biggest geospatial pet peeve is when people confuse the relationship between x/y and lat/long. I believe this is a fundamental concept in geography and I am here to reintroduce you to math you probably learned in elementary school (middle school maybe?). If you already know the proper x/y-long/lat relationship then you can skip the rest.

First, let’s review the Cartesian coordinate system. The X axis is the horizontal plane and the Y axis is the vertical plane. Two dimensional. Pretty simple.

Now, let’s look at latitude and longitude. Latitude measures angular distance from the equator to a point north or south of the equator. While longitude is an angular measure of east/west from the Prime Meridian.

Now this is the important part.

- Latitude values increase or decrease along the vertical axis, the Y axis.
- Longitude changes value along the horizontal access, the X axis.

Easy. X = Longitude, Y = Latitude. Now you will no longer be confused when calculating centroids or setting webmap coordinates.

Happy mapping!