Which NAD_1983_To_WGS_1984 to use ?

I often wonder which Geographic Transformation to use when going from NAD 1983 to WGS 1984 and when I'm faced with it I usually forget. Perhaps this blog post will be something I can refer back to when I need to. Apparrently after choosing one of the main three, it doesn't matter very much. The main three are _1 (for all of NA including Caribbean), _4 and, _5 for the lower 48. Perhaps its best to use 5 unless the area in question is outside the lower 48 (in which case you would use _1) as EPSG says that _5 supersedes _4.

Its so much easier to go from NAD 27 to NAD 83 as NADCON (the obvious choice for Americans) is just easier to remember !

See the ESRI Technical Article on this topic.