More sophisticated architecturally than the hastily erected depot, the general office building constructed in 1900 was designed by Seattle architect Henry Dozier. The forthright Classical Revival design features a balustraded and pedimented parapet, modillioned cornice, swag-and-garland frieze, and shouldered architraves on the second-story windows. Fluted box columns on the first level frame the storefront windows. Lettering declaring this the “Railroad Building” built in “1900” is of galvanized iron, as are many of the moldings.

The rest of the two-story building is wood, covered with a variety of vertical and horizontal sidings. The office building was connected to the depot by a second-level passageway. In 1908, the first floors were connected in the rear, enlarging the baggage and freight rooms. A band of windows in the rear at the second level illuminated the drafting room. Interior finishes in this building were also more sophisticated than for the depot. Here, the vertical-board wainscot was stained and varnished, while the walls were lathed and plastered. A two-story fireproof vault held gold shipments and company papers. At its completion in May 1900, the newspaper declared it “by far the finest wooden structure in the city.”