16 Pa. Stat. § 7351
The office of county controller is hereby established, and the office of county auditor or auditors abolished, in each county of this Commonwealth which shall contain by any Federal census one hundred thousand inhabitants or over. At the municipal election in the year one thousand nine hundred and thirteen the qualified electors of each such county, not now having a controller, shall elect one citizen of such county to serve as controller, in place of county auditor or auditors, until the first Monday of January, one thousand nine hundred and sixteen. At the municipal election in the year one thousand nine hundred and fifteen, and quadrennially thereafter, the qualified electors of each county entitled to a controller shall elect one citizen of such county, who shall serve as controller for the term of four years from the first Monday of January thereafter following, or until his successor shall be qualified, if he so long shall behave himself well.
16 P.S. § 7351