It was created on January 24, 1851, by the Oregon Territorial Legislature embracing the lands along the Umpqua River in southwestern Oregon.
[1] Gold had been discovered in the Umpqua region, which brought a rapid increase of settlers to the new county.
The first meeting of the Umpqua County Court was in Elkton in 1852; later the county government was moved to Green Valley and Yoncalla.
[1] On December 22, 1853, part of the western portion of the county was included in the newly formed Coos County.
Some accounts[2] state that politics caused the county's end.