Unusually among New York post offices in that style from that time,[2] it was built in a rough hexagonal shape so that its main entrance could face southwest, towards the corner.

"United States Post Office" is spelled out by bronze letters between the roundels, and "Mineola, New York" is carved into the frieze above the main entrance.

Unusually for a post office of this size built during the 1930s, there is no mural or other artwork of the type commissioned by the Works Progress Administration in the lobby.

In the early decades of the next century, improvements to rail and road transport led to the beginning of suburbanization in Nassau County and the Mineola area.

The site was purchased in 1933, and Peabody, Wilson & Brown, a New York firm best known for some large estates on Long Island such as Charles Millard Pratt's Seamoor in Glen Cove and the Huntington Town Hall.

Julian Livingston Peabody and his wife drowned in January 1935 in the sinking of the passenger liner SS Mohawk off New Jersey, and Archibald Manning Brown left the firm that same year to head the design team planning the Harlem River Houses, the first federally financed housing project in New York City.