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Old 01-22-2020, 07:59 AM
JKellyMap's Avatar
JKellyMap is offline
Join Date: Mar 2005
Location: Wisconsin
Posts: 10,337
Right. When the OP started by saying they wanted to use “this map,” did they really mean that very map — in which case, its projection would be important, and if unknown, it would have to be he referenced/rubber-sheeted to a base map with a known projection — OR did they actually mean “I want to use the DATA that is SHOWN in this particular map?”. Probably, the latter — and most replies in this thread have dealt with that. In other words, easier to make a new map with two layers: the lat-long points, and the underlying data displayed in the original map — which the OP will have to write into a table, and join (using GIS or otherwise) to an empty polygon file (easy to acquire) with the boundaries of the units used in the data (counties? States?).

Georeferencing as I described it is normally only used when the original map truly is the important document, typically Some old, historic paper map.