The Washington State Building was located on the north side of the Panama-California Exposition's Via de los Estados, adjacent to the New Mexico State Building. The structure was designed in an eclectic California-Mission style, and featured arches, buttresses, deep-set windows, and a terra-cotta tile roof. Curving facades, flanked by domed slope-walled towers, were situated at the building's west end; each containing five narrow arched-windows and projecting wood vigas. The building was entered through a Mission-style arch, which opened into a small patio; and an open terrace, placed on the building's north side, overlooked the lushly planted Palm Canyon. The interior was filled with the comprehensive exhibits from the State of Washington.