John Nunn, J.M. Tindall, and the 1936 construction
John Nunn was a Shamrock businessman in the mid-1930s who saw an opportunity in the growing Route 66 traffic crossing the Texas Panhandle and wanted to build a roadside filling station and cafe that would stand out from the dozens of generic stations already operating along the highway. The widely-told local story — preserved in the Pioneer West Museum and the U-Drop Inn's own interpretive signage — is that Nunn sketched the building's distinctive tower-and-canopy concept on the dirt outside the construction site using a nail, then handed the rough sketch to architect J.M. Tindall to develop into formal construction drawings.
Tindall translated Nunn's rough concept into a fully developed Art Deco design that drew on the architectural vocabulary fashionable in larger American cities during the mid-1930s — vertical massing, geometric ornamentation, glazed terra cotta tile, and integrated neon signage. The construction cost of roughly $23,000 in 1936 dollars was substantial for a small-town Texas commercial building (equivalent to several hundred thousand dollars today) and reflected Nunn's ambition for the project. The building opened in 1936 with a Conoco filling station occupying the south side and the U-Drop Inn Cafe occupying the north side under a single architectural envelope.
The name "U-Drop Inn" was reportedly selected through a community naming contest held in Shamrock in 1936, with a local boy winning a small prize for the playful suggestion. The cafe operated under that name for most of the building's history with a few intermittent renamings during ownership changes. The Conoco filling station continued under that brand until the 1970s when changes in the petroleum industry and declining Route 66 traffic made the small filling station unviable.