CNS in New York

Like I have read from other people, prior to starting this research, I have never heard of a CNS. I'm looking for info on what they do specific to New York and Long Island. I am a second degree program candidate and looking at my options for Dual Degree programs. Can CNSs get jobs on Long Island in hospitals or are they generally used in private practices. My primary interest is in ER. Can one get a job in an ER as a Trauma specialist CNS? I don't see any listings for CNSs at the big hospitals. Thanks for any advice.