datestamp on cover to Portland, Oregon, franked with 3c Rose with circular grid, trivial reduction at right, light aging, fine,

Ruby City was the original county seat of Owyhee County from 1863 to 1867. In 1864 Silver City was founded a mile to the south and quickly outgrew Ruby City, forcing the closure of its post office in 1867. Manuscript postmarks were used until 1866, placing this cover near the end of the post office's tenure.