S.D. Codified Laws § 1-29-1
Whenever, due to an emergency resulting from the effects of enemy attack, or the anticipated effects of a threatened enemy attack, it becomes imprudent, inexpedient, or impossible to conduct the affairs of state government at the normal location of the seat thereof in the city of Pierre, Hughes County, South Dakota, the Governor shall, as often as the exigencies of the situation require, by proclamation, declare an emergency temporary location, or locations, for the seat of government at such place, or places, within or outside of this state as the Governor may deem advisable under the circumstances, and shall take such action and issue such orders as necessary for an orderly transition of the affairs of state government to such emergency temporary location, or locations. The emergency temporary location, or locations, must remain the seat of government until the Legislature establishes a new location, or locations, or until the emergency is declared to be ended by the Governor and the seat of government is returned to its normal location.
SDCL 1-29-1