16 Pa. Stat. § 4963
At said meeting or at any subsequent meeting agreed upon, said board shall designate the depositories and the rate of interest to be paid by them to the county.
Depositories so designated shall, upon receipt of notice of their selection as a depository of county funds, furnish collateral to secure payment of deposits and interest to the county by depositing in escrow securities to be approved by the board. Such securities shall be of the kind and in the amount to be fixed by the board. Substitution of such securities may be made with the approval of the board in each case. The board may designate a branch bank of the Federal Reserve Bank of the district, located within the county, as escrow agent for the keeping of securities and to perform such functions as the board may prescribe.
The county treasurer, upon the designation of such depository or depositories, shall immediately transfer thereto all county funds to be deposited, and shall thereafter keep such deposits solely in such depository or depositories, in the name of the county. Withdrawals from such depository shall be only drawn by the treasurer upon properly authorized checks or by other commercially accepted methods for county fund transfers.
16 P.S. § 4963