When did the great basin become a national park?

Grand Teton National Park was first set aside by an act of Congress in 1929. This initial park included only the Teton Range and the six glacial lakes at the base of the mountains.

President Franklin Delano Roosevelt, through presidential proclamation in 1943, combined the Teton National Forest lands with other federal acres plus Jackson Lake plus a donation of land by John D. Reckefeller, Jr. into the Jackson Hole National Monument.

On September 14, 1950, the Jackson Hole National Monument and the original Grand Teton National Park were combined into a new Grand Teton National Park.