Oakdale is a city in the San Joaquin Valley and Stanislaus County, California. It is part of the Modesto Metropolitan Statistical Area. Oakā¦Oakdale is a city in the San Joaquin Valley and Stanislaus County, California. It is part of the Modesto Metropolitan Statistical Area. Oakdale goes by the slogan "Cowboy Capital of the World." The population was 23,181 at the 2020 census, up from 20,675 at the 2010 census and 15,503 at the 2000 census.