Pennsylvania constitution
Article IV: the executive
Section 14

In case of the death, conviction on impeachment, failure to qualify or resignation of the Lieutenant Governor, or in case he should become Governor under section 13 of this article, the President pro tempore of the Senate shall become Lieutenant Governor for the remainder of the term. In case of the disability of the Lieutenant Governor, the powers, duties and emoluments of the office shall devolve upon the President pro tempore of the Senate until the disability is removed. Should there be no Lieutenant Governor, the President pro tempore of the Senate shall become Governor if a vacancy shall occur in the office of Governor and in case of the disability of the Governor, the powers, duties and emoluments of the office shall devolve upon the President pro tempore of the Senate until the disability is removed. His seat as Senator shall become vacant whenever he shall become Governor and shall be filled by election as any other vacancy in Senate.