The Post Office Department acquired the building site in 1931, and construction was completed in 1933.

[4] The St. Johns Post Office is an example of a small community post office constructed in the 20th Century Georgian style (also Colonial Revival-style) typical of Depression Era federal architecture.

The building's Georgian style is suggested in the detailing of the arched Palladian windows and termination of the facade with a molded frieze and cornice.

[2] The building is also unique among small Oregon post offices in that it was designed by a local architect, Francis Marion Stokes,[2] who designed several architecturally prominent buildings in the Portland area, several of which are included in the city's historic resource inventory.

The murals depict the development of the neighborhood with significant historical events and prominent citizens.