I am trying to georeference three (1840, 1844, and 1877) northern Maine maps. I really am not able to find which datum to use. Can anyone point me to a list of historic and regional datums?

  • What is the scale of the maps? if the scale is low, say 1:250,000 or lower, you could use a modern datum, since the errors won't make much of a difference. – Devdatta Tengshe May 20 '13 at 4:14
  • Based on the years you gave, I'd bet that a datum wasn't even used. It was probably projected directly from an ellipsoid or spheroid. If you can figure out what projection the map is in, you might be able to derive the ellipsoid used and go from there. – Mintx May 20 '13 at 21:14

Why not use a modern datum?

I'd just georeference them to whatever is the current coordinate system used in Maine. That means you can use current imagery to connect to, where possible.

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