why don't POI locations match Mapsource


I want to edit the airport POI I downloaded to just the ones East of the Mississippi. When I looked at the specific coordinates in the file, they did not match the locations indicated when the same airports were located using Mapsource. Invariably the file indicated the location several miles West of the location indicated using Mapsource. I am using WGS 84 on Mapsource and thought this was the same used in most, if not all, POI files.

Any suggestions in resolving this?