From the record
“The United States Coast Guard Cutter Fir was the last lighthouse tender built specifically for the United States Lighthouse Service to resupply lighthouses and lightships, and to service buoys. Fir was built by the Moore Drydock Company in Oakland, California in 1939.”
Wikipedia article USCGC Fir (WLM-212), CC BY-SA 4.0.
One of 324 National Register listings published here for King County · listed in 1992 · category: Structure · built in 1939 · a National Historic Landmark.
Sources: the Wikipedia article · the National Register database, National Park Service