Merrill's first post office was located in the Jenny Hotel, owned by Cyrus Stowbridge, the first postmaster. Later, the post office rented space in the Masonic Temple. In 1915, the U.S. Office of the Supervising Architect designed and built the new Merrill Post Office, the first federally owned post office in Merrill. It is one of several Neo-Classical Revival style buildings in the downtown business district of Merrill.

The Merrill Post Office is one of a few examples in Wisconsin of a post office built during the transition into the McAdoo System, which standardized the designs and construction of post offices. Therefore, while displaying a greater degree or originality than subsequent post office designs, some architectural features are found at other post offices. The building’s classical design is visible in its temple-motif façade, with brick pilasters and pediment, as well as the dentilled cornice. Using brick (instead of cut stone) in conjunction with the classical design elements was a common money-saving technique for post office construction.

The lobby displays coffered ceilings and marble wainscoting and door surrounds. The central feature of the Merrill Post Office is its unique ceiling with an octagonal skylight. It contains its original leaded glass and provides light to the main lobby of the building.

The Merrill Post Office is open during normal business hours.