Lone Mountain RV Resort & Campground

O'Brien is an unincorporated community in Josephine County, Oregon. Lone Mountain RV Resort is located in O'Brien, just off HWY 199 on Lone Mountain Rd.  In 1899 an early settler, John O'Brien settled in the area that would later be named in his honor, O'Brien, Oregon. Although the date of establishment for the post office is unknown, it was a log cabin moved from Waldo. In 1937 the building, which is still standing today as the O'Brien Store, served as both a post office and a store. O'Brien was established as a crossroads, and later, a mill was built near the town.