N.Y. Second Class Cities Law § 19

§ 19. Holding more than one office. No person shall, at the same time,\nhold more than one city office. Upon the acceptance by a city officer\nof a second office the office first held by him shall thereupon become\nvacant. The term "city officer" as used herein, however, shall not be\ndeemed to include a commissioner of deeds.\n