This 103,000-acre national monument was designated in 2000, and expanded in 2017. Drawing from two different reports compiled by the scientific community as well as a legislation introduced in the Senate in 2015, the January 2017 expansion protects more than 42,000 additional acres of public land in Oregon and approximately 5,000 acres in California to increase vital habitat connectivity, watershed protection, and landscape-scale resilience for the area’s unique biological values, particularly in the face of growing impacts from climate change.

At the intersection of the Cascade, Klamath and Siskiyou Mountain ranges, the rugged, remote region has tremendous biodiversity. Elevational changes, moisture patterns, and a unique assemblage of geologic formations create a veritable “Ark” of biodiversity. This ecological diversity includes three endemic freshwater fishes, Jenny Creek’s freshwater snail populations, rough skinned newts, kangaroo rats, pygmy nut hatches and northern spotted owls. Cultural history is also widespread throughout the monument with almost 100 sites of prehistoric use, and more recent signs of pioneer history throught the Applegate and Oregon-California Trail.