The state plane coordinate systems use NAD27 or NAD83 (plus improvements).<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;State_Plane_Coordinate_System" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;State_Plane_Coordinate_System</a><p>The flattening of an orange peel you mention is more about projection, a datum is a mathematical description of the earth that maps out how geographic coordinates will vary. Given geographic coordinates, a projection system is needed to display them on a flat surface (or really any surface that doesn&#x27;t match the shape of the geographic coordinate system).<p>Differences between datums do arise from different modeling choices and should be accounted for when translating coordinates, but as the fine article discusses, the offsets in GCJ-02 are algorithmic and are not a refinement of WGS84, they obscure true location.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Restrictions_on_geographic_data_in_China#GCJ-02" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Restrictions_on_geographic_dat...</a>