 This video will provide you with the basics of working with coordinate systems for vector geospatial data within ArcGIS Pro. I've created a new ArcGIS Pro project using the map template. By default, the World Topographic map was selected as a base map, but anytime I can go in and change the base map using the menu options from above. Each base map has a coordinate system associated with it. It's this coordinate system that allows me to overlay other geospatial data and do geospatial analyses. We can explore the coordinate system of any layer loaded in ArcGIS by going to its properties, clicking on the Source tab, and then navigating over to the Spatial Reference Information section. This base map, as with most base maps, make use of the Web Mercator Auxiliary Sphere coordinate system with the WGS1984 datum. This is an excellent coordinate system for global mapping, but it has some limitations at the local scale. My map also has a coordinate system associated with it. By default, it will adopt the coordinate system of the first layer in ArcGIS Pro, the base map. So the coordinate system for my map data frame will be Web Mercator Auxiliary Sphere. Because I'm working in 2D mapping space, I don't have a vertical or Z coordinate system associated with my data frame. I'm now going to add a vector layer to this project. Ahead of time, I went to the Vermont Geodata Portal and downloaded the Vermont Boundary. I stored the boundary in my Project Geodata Base. Just as I did with my base map layer, I can find out the coordinate system associated with the Vermont State Boundary by right clicking on it, going to its properties, going to the Source tab, and examining the Spatial Reference section. From this information, we can see that the State Boundary is in Vermont State Plain Nat 83 with the unit of measurement being meters. Vermont State Plain Nat 83 meters is a standard coordinate system used for mapping in Vermont. Because the Vermont Boundary feature class was the first non-base map layer loaded into ArcGIS, my map data frame has adopted the State Plain coordinate system as its coordinate system. By going into the properties of my map data frame, we can see that the coordinate system has now changed from Web Mercator Auxiliary Sphere to Vermont State Plain. Now let's add another vector feature class, the National Forest System Trails, for the entirety of the United States. Exploring its properties, we see that it has a geographic coordinate system, meaning that it's unprojected data. Even though the base map, State Boundary, and Trail layer have different coordinate systems, ArcGIS is able to overlay them through projection on the fly technology. If these coordinate systems were not defined, we wouldn't be able to overlay these layers. Right now ArcGIS is projecting on the fly all of these layers into the Vermont State Plain coordinate system. The State Plain coordinate system is wonderful for mapping in Vermont, but if we zoom out, we can see that the base map and the trail network are distorted. We simply wouldn't want to use this coordinate system if we were doing any mapping outside of the state of Vermont. At any time we can go in and change the coordinate system of our map data frame, and it'll project on the fly all the layers with defined coordinate systems to match this new coordinate system. Here I'm switching over to the geographic coordinate system used by the trails layer. When we move to that geographic coordinate system, you can see the shape of Vermont gets distorted. The unit of measurement is decimal degrees for this coordinate system, which isn't good for any type of analysis. However, geographic coordinate systems are useful for displaying data over very large areas. We can also choose the coordinate system of the data frame so that our map is in a coordinate system different than any of our layers. In this case I'm going through and I'm choosing the contiguous USA Albers Equal Area coordinate system. This is a great coordinate system for mapping in the United States, but as you can see it distorts the rest of the world. In this tutorial we gave you a quick introduction of the basics of coordinate systems within ArcGIS. We discussed how your map data frame has a coordinate system and all the layers within your map have a coordinate system. Your map data frame controls the coordinate system that all layers are projected into. So if your map data frame is set to Vermont State Plain, all of your other layers are projected or temporarily transformed on the fly to match that coordinate system. Having a correctly defined coordinate system is absolutely crucial to getting your data to overlay correctly. Selecting the appropriate coordinate system depends on the type of analysis that you're doing. For local scale mapping, a state plane coordinate system will work well. For global scale mapping, you may want to use a geographic coordinate system. Thank you for watching.