South dakota constitution
Article XVIII: banking and currency
Section 1

If a general banking law shall be enacted it shall provide for the registry and countersigning by an officer of this state of all bills or paper credit designed to circulate as money, and require security to the full amount thereof, to be deposited with the state treasurer, in the approved securities of the state or of the United States, to be rated at ten per centum below their par value, and in case of their depreciation the deficiency shall be made good by depositing additional securities.