From the record
“Mayer Boathouse is located in Three Lakes, Wisconsin, United States. It was added to the National Register of Historic Places in 2011.”
Wikipedia article George P. Mayer Boathouse, CC BY-SA 4.0.
One of 20 National Register listings published here for Oneida County · listed in 2011 · category: Building · built in 1920.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service