Buchanan became the commercial center of the surrounding area in the 1840s, and the business district developed rapidly in the 1850s. In 1848, business partners Lorenzo Alexander and John Ross built a two-story stone commercial building in Buchanan, and in 1850 the pair established a general store. By 1860, the business partners had constructed a three-story brick commercial block, the Excelsior Block, in downtown Buchanan near this location. In 1862 Ross and Alexander started a second project, the Union block. However, in 1862 a devastating fire swept through the area, destroying a number of commercial buildings including the Excelsior Block, but sparing the partially built Union Block. The building was completed the next year.[2]
The building was used for commercial businesses on the first floor and professional tenants on the second floor. The first commercial tenants were likely J.D. Ross's dry goods store and a second dry goods store owned by Ross and Alexander. Subsequent tenants included businesses selling dry goods, groceries, hardware and other items. One of the storefronts housed a succession of hardware stores for almost 100 years, from at least 1896 through 1994. Professional tenants on the second floor included doctors, barbers, lawyers, and others, but the last tenant departed in the 1940s. The third floor was originally a large hall, but at some point (perhaps as early as 1870) was divided into two spaces. These spaces were used for public events, including dances, socials, performances, and religious services.[2]