Alderdale is an extinct town in Klickitat County, in the U.S. state of Washington. The GNIS classifies it as a populated place.
A post office called Alderdale was established in 1907, and remained in operation until 1962. The community took its name from nearby Alder Creek.
Coordinates: 45°50′05″N 119°55′15″W / 45.83472°N 119.92083°W