ArcMap projects data on the fly. This means that it is possible to create an ArcMap document in a coordinate system or projection using data that are projected to many different coordinate systems.
The Coordinate System of the Data Frame is set by default to the coordinate system of the first layer added to the Data Frame.
Instructions provided describe how to check the coordinate system of the ArcMap Data Frame, and of the individual data layers in the map.
- Check the Coordinate System of the ArcMap Data Frame by navigating to View > Data Frame Properties and click the Coordinate System tab.
- Check the coordinate systems of each layer in the map individually by right-clicking on the name of the layer > Properties and click the Source tab. The Coordinate System of the layer is displayed in the Data Source box.
- Check the coordinate systems of all data in the map by navigating to View > Data Frame Properties and click the Coordinate System tab. Under 'Select a coordinate system', open the folder named Layers, and the folder for each set of data in the Data Frame. The projection definition names are displayed.