In the 1930s, the Federal government built hundreds of post offices with federal funds. This construction helped spur the local economy in Littleton through the purchase of local construction materials and employment opportunities the project provided. The building was the first constructed solely for use as a post office in Littleton. The construction of an addition in 1962 demonstrates the need for larger facilities to serve the growing population of Littleton in the post-World War II era. The Post Office is also a representative example of a Colonial Revival-style public building, with character-defining features such as its brick construction, side-gabled roof with center cupola, symmetrical façade with evenly spaced multi-light windows, cornice with dentils, and elaborate entrance topped by a decorative metal eagle. The 1962 addition continues the Colonial Revival styling with more restrained use of detail, as is typical of that era.