The Yellowstone Main Post Office in Yellowstone National Park was built in Mammoth Hot Springs as part of a facilities improvement program by the United States Post Office Department. The post office in Yellowstone was nominated to the National Register of Historic Places as part of a thematic study comprising twelve Wyoming post offices built to standardized USPO plans in the early twentieth century. The Yellowstone facility is an understated classical structure with a low hipped roof and rounded dormers that uses a plan and a basic design vocabulary similar to that used in other post offices in the program. It is somewhat at odds with the prevailing design theme expressed in other buildings in the former Fort Yellowstone district.
