16 U.S. Code § 12 - Aid to visitors in emergencies
The Secretary of the Interior is authorized to aid and assist visitors within the national parks or national monuments in emergencies, and when no other source is available for the procurement of food or supplies, by the sale, at cost, of food or supplies in quantities sufficient to enable them to reach safely a point where such food or supplies can be purchased: Provided, That the receipts from such sales shall be deposited as a refund to the appropriation or appropriations current at the date of covering in of such deposit and shall be available for the purchase of similar food or supplies.
Source(July 3, 1926, ch. 792, § 1,44 Stat. 900.)