Flourishing agricultural enterprises were served by railroads and harbors that facilitated trade with both the continental United States and East Asia.

Whitfield designed the building in the Mediterranean Renaissance Revival style, which blends traditional classical architecture with features more suited to a tropical climate.

Louis A. Simon, supervising architect of the US Treasury, designed the wings in a style compatible with that of the original building.

The building was added to the National Register of Historic Places listings on the island of Hawaii on October 1, 1974 as site 74000708.

In 1978, most postal functions moved to a new location, and the following year the Third Circuit Court vacated the third floor, which was converted into offices.

[4] Whitfield's design blends classically inspired forms and motifs with features that are suitable for the warm Hawaiian climate.

Open-air loggias divided into three distinct levels face the courtyard and provide occupants with pleasant views and circulating air currents.

Decorative elements within the courtyard, including colorful mosaic tiles and urns, emphasize the Mediterranean Renaissance Revival style of the building, which blends classical and exotic motifs.

[3] The exterior is divided into horizontal zones by water tables and stringcourses, a feature common to Renaissance Revival architecture.

On Memorial Day in 1922, the American Legion planted 17 royal palms along Kekaulike Street to commemorate Hawaiian citizens who died in World War I.