The Mercantile Bank of Southern Maryland is a two-story, brick commercial building designed in the Classical Revival-style. Constructed in 1921, it serves as the southern visual terminus for Washington Street. Its classical design illustrates a style commonly used by banking institutions on the early 20th century. This building served as a symbol of the economic prosperity of Leonardtown - a town that was increasingly seen as not only the seat of government, but as the social, religious, commercial, and financial center of St. Mary's County.