In January, 1908, Alexander Boehme (1879-1954) entered into a 20 year lease with Johanna Wengenroth (widow of Phillip Wengenroth) for one acre of land for the purpose of erecting and maintaining a mercantile establishment with dwelling attached. The rent was $1.00 per year with privilege of receiving or selling all improvements erected during this lease. The Castroville Anvil Sparks Newspaper, February 10, 1908 issue, reports: "San Geronimo can soon boast of a grocery store as Mr. Alex Boehme began the erection of the necessary buildings on last Monday." The Castroville Quill Newspaper, April 10, 1908, ran this advertisement: "San Geronimo Store - Dealer in - General merchandise, Hardware, Tinware and Crockery, Country Produce. Alex Boehme, Proprietor."

A dwelling was built on the north side of the store. Mr. Boehme applied to The Post Office Department, Washington DC, for establishment of a Post Office within the San Geronimo Store in 1908. The name San Geronimo Post Office was not approved and instead, the name was changed to Rio Medina Post Office; Alex Boehme was appointed postmaster. In 1908, the Medina-San Geronimo Telephone Company was founded and the lines around San Geronimo and northeast were hooked into a switchboard in the San Geronimo Store. The store sold groceries, hardware, feed, dry goods, notions and patent drugs, and offered banking services to customers. Until the mid-1930's a Delco generator supplied electricity.

In the years since it first opened, the building has grown, moved locations, changed names and postmasters several times. It's been home, at one time or another, to a saloon, dance hall, cotton gin, meat market and automotive garage. In 1928, Mr. Boehme sold his share of the business to Alfred Rihn, who leased new land and built a new store on the south side of the original building. This original San Geronimo store was restored in 1993 and is the structure you can now visit today.