Oregon City was the first city in the United States west of the Rocky Mountains to be incorporated. It is the county seat of Clackamas County, Oregon. As of the 2000 census, the city population was 25,754; the 2006 estimate has the population at 29,540. The city's motto is Urbs civitatis nostrae prima et mater (First and mothertown of our state), as seen on the city's seal.