Hi, Jim,
I am the director of a medium sized library on the North Shore of Long
Island.  In our LI History collection we do have a book of Sanborn maps
which has been donated by a local resident.  We have had the book of maps
preserved and copied.
The maps are an invaluable snapshot of our City from almost eighty years
ago.  They particularly concentrate on the water system throughout Glen
Cove.  I am not aware of any fire insurance aspect of them.
Our collection is open Monday afternoons from 2 to 5pm, but if you would
like to come out another time and see the maps we could arrange it - just
give me a call.
Antonia Petrash, Acting Director
Glen Cove Public Library
516 676 2130