Cascade National Forest was established by the U.S. Forest Service in Oregon on March 2, 1907 with 5,886,840 acres (23,823.2 km2) when its name was shortened from Cascade Range National Forest and land was added. On July 1, 1933 the entire forest was combined with Santiam National Forest to establish Willamette National Forest.
References
Cascade National Forest Wikipedia(Text) CC BY-SA