This one's bugged me for a while, and I finally decided to do a quick bit of research to check up on it. The state HP of NJ, elevation 1803', is listed as having 1783' of prominence. Having visited it twice (and driving through the area many times), it's obvious that High Point is fairly prominent for the area, but that figure seems excessively high. I checked and found a real prominence somewhere closer to 908', with the line parent being in Ulster County NY.
According to peakbagger.com, key saddle is here, which agrees with my own analysis:
http://mapper.acme.com/?ll=41.47584,-74.55337&z=15&t=T
~Chris