I have a feature class that has been processed and says that the projection is in WGS 1984 Web Mercator Auxiliary Sphere.

enter image description here

However, I suspect that it is NOT truly in WGS 1984 Web Mercator Auxiliary Sphere. I suspect that it is still in its pre-processed projection, GCS North American 1927. Unfortunately I cannot get the source data prior to being processed and still in its original format of GCS North American 1927.

How can I accurately test to see if this dataset is truly in WGS 1984 Web Mercator Auxiliary Sphere or GCS North American 1927?

ArcGIS Desktop 10.3.1

  • 1
    Only when using other data with know coordinate reference for comparing known points or recognisable features.
    – Matte
    Jul 27, 2016 at 18:36
  • If it is in EPSG::3857, data located around Hutchinson or Roberts counties in the Texas panhandle.
    – mkennedy
    Jul 27, 2016 at 23:44

2 Answers 2


Look at the extent in your image. If your data was not reprojected but instead just defined incorrectly, the X extent should be around -60 to -170 and the Y extent should be around 25 to 50. Your data would also be showing up somewhere off the coast of Ghana in Africa.

Given the extent values, it's a safe bet that your data is really in WGS84 Web Mercator. Now, whether the transform from NAD27 to WGS84 was done properly, that's a completely different question.


Try using the free and open source ogrinfo utility to describe the layer. It has lots of switches and options for displaying various feature class attributes.


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