If you create a map and the coordinate system is not set (i.e. if the Name is Unreferenced local system), but you have an Esri PRJ file containing the coordinate system information, you can load the file for your map layer.
- Select the map layer (Contours, Color Relief, etc.) in the Contents window.
- Click to the Coordinate System page in the Properties window.
- Click the Set button.
- In the Assign Coordinate System dialog, click the Load from File button.
- Select your PRJ (or GSR2, GSR, or WKT) file and click Open.
- Click OK and that coordinate system is assigned to your map layer.
Updated September 26, 2017