Clackamas County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 421,401, making it Oregon's third-most populous county. Its county seat is Oregon City. The county was named after the native people living in the area at the time of the coming of Europeans, the Clackamas people, who are part of the Chinookan peoples.

Oregon City is the county seat of Clackamas County, Oregon, United States, located on the Willamette River near the southern limits of the Portland metropolitan area. As of the 2020 census, the city population was 37,572. Established in 1829 by the Hudson's Bay Company, in 1844 it became the first U.S. city west of the Rocky Mountains to be incorporated.