N.Y. Veh. & Traf. Law § 1165

§ 1165. Method of giving hand-and-arm signals. All signals herein\nrequired given by hand and arm shall be given from the left side of the\nvehicle in the following manner and such signals shall indicate as\nfollows:\n 1. Left turn. Hand and arm extended horizontally.\n 2. Right turn. Hand and arm extended upward.\n 3. Stop or decrease speed. Hand and arm extended downward.\n