The St. Helena Southern Pacific Railroad Depot embodies the traditional pattern book architectural style and construction techniques of a late 19th century Southern Pacific depot in California.

It is the only intact example of a Southern Pacific depot in Napa County. The Yountville Southern Pacific Depot was converted into tourist shops and only the two-story section remains. The freight and loading areas were demolished in the 1970s.

The Calistoga Depot did serve as a Southern Pacific depot, but because it was built by the Napa Valley Railroad around 1868 before the founding of Southern Pacific, the Calistoga Depot has none of the characteristic of a Southern Pacific depot.

Source: Adapted from the NRHP nomination submitted in 1996.