 Prairie Ridge is located at (47.145326, -122.148230).According to the United States Census Bureau, the CDP has a total area of 4.3 square miles (11.1 km²), of which, 4.3 square miles (11.0 km²) of it is land and 0.23% is water.As of the census of 2000, there were 11,688 people, 3,902 households, and 3,109 families living in the CDP.