In 1975 the voters of Polk County approved the appropriation of funds to purchase the former post office building and to build a modest-sized annex to it. The project was to encompass some restoration of the old building and to remodel its rear section and add space for additional county offices. The architects sheathed the addition in a matching limestone, kept the general height and scale of the older building, and carried an abstracted version of the entablature/cornice of the older building around the new building. They provided for a symmetrical south facade with a central solid block, and a portico on each side. Instead of employing columns or piers, they utilized a pair of three freestanding fin-walls, which end up reading as both traditional and contemporary design features. The county office building in conjunction with the old post office building represents one of the most sensitive additions/ adaptive reuses of the decade of the 1970s in Iowa.