Roseburg is the most populous city in and the county seat of Douglas County, Oregon. It is located in the Umpqua River Valley in southern Oregon. Founded in 1851, the population was 23,683 at the 2020 census, making it the principal city of the Roseburg, Oregon Micropolitan Statistical Area. The community developed along both sides of the South Umpqua River and is traversed by Interstate 5.