From the record
“The Double-O Ranch Historic District is located west of Harney Lake in Harney County in southeastern Oregon, United States. At one time, the Double-O Ranch covered over 17,000 acres (69 km2).”
Wikipedia article Double-O Ranch Historic District, CC BY-SA 4.0.
One of 7 National Register listings published here for Harney County · listed in 1982 · category: District.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service