From the record
“Tom Sun Ranch, also known as Sun Ranch, is a historic site along the old Oregon and Mormon trails, about 6 mi (9.7 km) west of Independence Rock, Wyoming on Wyoming Highway 220.”
Wikipedia article Tom Sun Ranch, CC BY-SA 4.0.
One of 43 National Register listings published here for Carbon County · listed in 1966 · category: Building · a National Historic Landmark.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service