The North America gravity database as well as database from Canada, Mexico and the United States are being revised, and the revision includes the following two items: the use of the internationally accepted terrestrial ellipsoid for the height datum of gravity stations rather than the conventionally used geoid or sea level, and the modification of procedures for calculating gravity anomalies, including corrections for theoretical gravity, atmospheric effect, height effect, Bouguer effect, indirect effect, terrain and bathymetry effect, and isostatic compensation effect.