From the record
“The Hollenberg Pony Express Station, also known as Cottonwood Pony Express Station, is the most intact surviving station of the Pony Express in the United States. Hollenberg in 1858, to serve travelers on the Oregon and California Trails, and was used by the Pony Express when it was established in 1860.”
Wikipedia article Hollenberg Pony Express Station, CC BY-SA 4.0.
One of 7 National Register listings published here for Washington County · listed in 1966 · category: Building · built in 1857, vernacular architecture · a National Historic Landmark.
Sources: the Wikipedia article · the National Register database, National Park Service