Andy,
there were hundreds of them.
I have never seen an actual map or list that lists and locates them all, (someone somewhere probably has one)
but imagine one protecting EVERY block!
from binghamton all the way out to Hornell and beyond.
and probably East of Binghamton and West of Hornell too..
anywhere you have a mainline target signal today there was probably a semaphore.
In the 80's there was one in Waverly, heading East there were two at the next block just past the eastern end of Broad st extension.
2 more out in Barton..then many many more heading out to Binghamtom..lots of them!
I know where the tower for the Waverly semaphore is..
email me off list.
Scot