Oak Grove is an unincorporated community in Clackamas County, Oregon, United States, in the Portland metropolitan area. For statistical purposes, the United States Census Bureau has defined Oak Grove as a census-designated place (CDP). The census definition of the area may not precisely correspond to local understanding of the area with the same name. The population was 16,629 at the 2010 census.HistoryOak Grove was named at the suggestion of Edward W. Cornell, a member of the surveying party that platted the townsite in the 1890s. The company that was developing the property had not been able to come up with a good name for the place, and Cornell suggested "Oak Grove" after a crew ate lunch in a stand of oak trees in the northwestern part of the tract.The area was served first from the Milwaukie post office. In 1904, Creighton post office was established, named for Susan Creighton, on whose donation land claim the office stood. Postal authorities did not name the office "Oak Grove" in order to avoid duplication. There had once been an Oak Grove post office in Josephine County. The first postmaster was noted Oregon botanist Thomas J. Howell.
