Why don't these data appear in the right place?

Blog Post created by dkwiens Champion on Feb 13, 2015

This question almost always boils down to knowing the difference between Defining a Projection and Projecting Data.


  • Define Projection
    • Your data was created using some coordinate system. The data itself knows those coordinates, however, the file may not know what coordinate system it is supposed to use. Use Define Projection to tell the data (which, in turn, tells ArcMap) what coordinate system to use.
    • Define Projection is used to assign a known coordinate system to an unknown coordinate system.
  • Project
    • If you want to switch projections for some reason (e.g. to lessen certain inherent projection-specific bias), use the Project tool.
    • Project is used to assign a different known coordinate system to data (that has a known coordinate system)