The area originally was inhabited by the Umpqua Indians, who belonged to the Chinook tribe. Following the Rogue River Indian War in 1856, all remaining natives were moved by the government to the Grand Ronde Indian Reservation.

Douglas County was created on January 7, 1852, from the portion of Umpqua County which lay east of the Coast Range summit. In 1856 the Camas Valley was annexed to Douglas County from Coos County. In 1862, the rest of Umpqua county was absorbed into Douglas County, some say due to the loss of population following the end of the early gold boom, while others attribute the absorption to politics. Further boundary adjustments were made with Jackson and Lane Counties in 1915.