The NYC AC&C releases 2 lists every night. One for the public that only lists dogs available for public adoption, and one for rescues that list all the dogs that will be killed the following day (except the dogs on hold with the Dept of Health.)
This graph shows how many dogs were killed (by month) at each of the 3 NYC shelters, and if they were available to the public, or just rescues.
*SIACC does not kill at their location, but they ship the dogs to Brooklyn if they will be on the list that night.