Wyoming Permanent Mineral Trust Fund
The Wyoming Permanent Mineral Trust Fund (WPMTF) is a sovereign wealth fund of the U.S. state of Wyoming. Established in 1975 by constitutional amendment, it is funded by a 1.5 percent severance tax on "coal, petroleum, natural gas, oil shale, and such other minerals".
Source: Wikipedia — Wyoming Permanent Mineral Trust Fund (CC BY-SA 4.0)