Lolo National Forest spans about 2 million acres in western Montana along the Idaho border, west of the Continental Divide, and includes four wilderness areas around the Missoula region. Established on September 20, 1906, from four earlier forests, it later expanded through additions from other national forests. Its mix of continental and maritime weather creates unusually high biodiversity, with around 1,500 plant species and abundant wildlife, including bears, wolves, elk, moose, eagles, and swans. The forest also contains more than 100 named lakes, five rivers, extensive trails and campgrounds, and historic routes and sites tied to the Nez Perce, Lewis and Clark, and regional conservation work.