Oak Grove, in a flat green valley at the base of Palomar Mountain, was an important place in southern California history along the southern Immigrant Trail, later known as the Butterfield Trail. A stage station built there became a horse-changing and food stop when John Butterfield’s stage line began operating in 1858, carrying mail and passengers between St. Louis and San Francisco on a 2,800-mile trip that took about 24 days. Stage travel through Oak Grove continued until the Civil War intensified in 1861, when southern routes became unsafe and service was discontinued and moved north. In the fall of 1861, Oak Grove became the site of Camp Wright, an Army post established because the Union feared a Confederate invasion might use the Butterfield Trail to capture California, and a detachment of 250 men was sent there to protect the state. The camp was disbanded in 1866. Shortly after the U.S. Forest Service was formed in 1905, a ranger station and tree nursery were built there, and the Oak Grove Ranger Station served as the district ranger’s office and the main base for fire suppression activities and backcountry patrols. Since the turn of the century, the Forest Service has been and continues to be an important part of the area’s history.