Pennsylvania constitution
Article IX: local government
Section 13

(f) Upon adoption of this amendment all county officers shall become officers of the City of Philadelphia, and until the General Assembly shall otherwise provide, shall continue to perform their duties and be elected, appointed, compensated and organized in such manner as may be provided by the provisions of this Constitution and the laws of the Commonwealth in effect at the time this amendment becomes effective, but such officers serving when this amendment becomes effective shall be permitted to complete their terms.