The mayors of cities of the second class A shall, within thirty days after the effective date of this act, designate, in writing to the city clerk, the appointment of a deputy mayor in accordance with the provisions of this act. Any person, elected mayor of a city of the second class A, or vested with the power of mayor shall, within the period of thirty days after assuming the duties of said office, file a designation in the city clerk's office, in writing, appointing a deputy mayor in accordance with the provisions of this act.
53 P.S. § 30354