Gillette City Hall (1936) is located in the City of Gillette in the northcentral portion of the Powder River Basin in northeastern Wyoming. The building is located in the downtown commercial district at 400 South Gillette Avenue. It occupies the southwest corner of the intersection of South Gillette Avenue and West Fourth Street. The corner lot on which it is located is 140’ E-W x 75’ N-S. The original City Hall is a tall one-story building (90’ E-W x 50’ N-S) with a later two-story west addition (33’ E-W x 60’ NS). This brick building is a modest example of Art Deco architecture, exhibiting such features as a symmetrical façade, a stepped brick pavilion (main entrance) and a variety of decorative brickwork. Windows feature rowlock brick sills and soldier brick lintels. An early twentieth-century residential neighborhood is situated directly west of the building; in all other directions is a variety of commercial and civic buildings, many of which were also constructed with brick. The building has modest landscaping, with a small lawn and shrubbery on the east and part of the north sides. Gillette Main Street has installed a four-sided clock nearby that lends a historic ambiance to the immediate area, along with street signs and lampposts of a similar nature. A new city hall was built in 1984; however, the term City Hall or Gillette City Hall refers to the 1936 building in this nomination.

Gillette City Hall (1936) is eligible for inclusion in the National Register of Historic Places as a locally significant building under Criterion C. The period of historical significance dates to 1936, when the building was constructed. Notable dates in the history of the building include 1936, when the building was constructed and first occupied; 1967, when the two-story fire department west addition was constructed; 1974, when the fire department moved to a new building; 1978, when the city hall offices moved; and 1984, when the police department moved, and the building was put up for sale by the City of Gillette. Gillette City Hall served as the city hall, fire station, city jail, and community meeting place. This building was constructed during the Great Depression without the aid of any federal funding via New Deal programs. Construction was financed entirely by the City of Gillette, a fact that was touted in the local newspapers as a source of community pride and self-sufficiency. Gillette City Hall (1936) is locally significant under Criterion C, as a property that embodies the distinctive characteristics of a type, period, or method of construction. The building represents a modest example of Art Deco architecture, a part of the modernistic style popular in America from about 1920 to 1940.

The Gillette Post Office is a well-preserved example of a classical revival of the mid-1930s. This building displays a quality of design and craftsmanship that marks the building as one of the finest high style buildings in the county. As one of Gillette's first federal buildings, its construction was a major event in the city. In addition, the post office, which represented the link between the federal government and the local community, acted as a symbol of the federal government. The post office further signified the massive public buildings programs of the 1930s, specifically the Public Works Administration (PWA), that were intended to assist local communities during a period of national economic emergency. This building, eligible under Criteria A and C, is significant to the town of Gillette due to its use of classical design, its representation of the federal government, and the jobs provided during its construction.

Constructed in 1935 via the PWA, the post office is a five bay brick building. While the majority of the building is one-story, the façade is two. The post office has a primarily rectangular footprint, a flat roof, sits on a concrete foundation, and is devoid of much ornamentation. Although the interior of the building underwent multiple alterations, the exterior remains relatively intact. Since serving as the local post office, it became City Hall, a restaurant, and is currently under construction for a new retail business.

The Gillette Post Office contains some minimal classical elements. The building retains a few classical details in the sandstone pediment, cornices, and keystones. Since construction, the exterior of the post office had few alterations. There are no additions to the building, the windows and front entrance are original, even the rear loading dock still maintains its design and function. One of the few exterior alterations is the boarding shut of one set of the rear double doors. The integrity of the location, material, design, and craftsmanship are good, even though the setting is slightly altered as downtown of Gillette has changed somewhat over the past 73 years. Although the interior exhibits only a few of the characteristics of the original building, the feeling of the post office is maintained on the exterior.

Few monumental buildings existed in Gillette, thus providing distinction for the post office. In a small town, a classical revival was an anomaly. In addition to the architectural design and size of the building, the post office represented a federal presence in the town. Located in the county seat and the largest city in the county, this building, which was one of the only federal buildings in the area, represented the federal government to the local community. As stated in the Multiple Property Listing, the ''buildings in their architectural form exhibit an important symbol of the federal government, and its relationship to the local community.''

In Gillette, the building not only became a federal presence to the community, it also served as an opportunity for the citizens to interact with the government. Local leaders communicated with the Department of Treasury regarding plans, contractors, size, and design of the building. They also maintained contact with the Wyoming Representatives in Washington D. C. The City of Gillette formally submitted a request of $77,000 for the construction of a new post office building via the PWA program. Congress approved the proposal, but only appropriated $64,000. In April of 1934, a group of local citizens appealed for additional money to complete a full second floor for the building; however, Congress denied Gillette the funds. These same individuals requested U.S. Senator Robert D. Carey to continue the appeal.

Beyond the physical building and interaction with the government, the actual construction became an example of the public works programs developed by the federal government. The PWA hoped to promote employment and increase purchasing power through the construction of public works projects. For the 6 April 1935 edition, the News-Record, the local paper, interviewed Louis Blauner, President of the Blauner Construction Company, contracted to build the post office. He stated, ''All labor on the edifice will be furnished by local men as one of the main objects of the government's building of federal buildings is to help each individual community.'' As with the rest of the country, Gillette suffered from the Great Depression and the construction of a new building offered some relief to city residents. The News-Record continually addressed the shortage of work with a nearly daily article discussing the number of jobs available due to government subsidy programs.

The Gillette Post Office derives its significance from its impact on the local community during 1934-1935. The post office provided an example of designed architecture infrequently seen in an isolated Wyoming town. The building itself offered a tangible representation of the federal government to the small community of Gillette. In addition, its construction provided an influx of money to the local economy and a representation of the programs developed by the federal government, specifically the PWA, to provide jobs.