Wyo. Stat. § 36-10-106: Yellowstone National Park; reservation of jurisdiction by United States.

By section 2 of the Act of Admission of the state of Wyoming, 26 United States Statutes at Large, 222, chapter 664, the United States of America reserved exclusive control and jurisdiction over Yellowstone National Park and future additions to Yellowstone National Park. The boundaries of Yellowstone National Park at the time of admission were defined in 17 United States Statutes at Large 32.