When postal service automation arrived in the 1960s, the federal building could not accommodate the new machinery, and a 900-foot-long rectangular building was erected near the new train station. A band of Lannon stone cladding is sandwiched between two precast concrete layers, and a concrete parapet hides the mechanical systems. The rusty-looking Cor-Ten steel exterior accents were a Milwaukee first, and the curved exterior stairs offer a rakish entrance to the facility. A rail siding feeds into the building’s south side, and mail trucks use a spiral ramp entering the east side. In addition to its role as Milwaukee’s main post office, it is the largest processing and distribution center in Wisconsin, employing 3,600 people. Seven million pieces of mail pass via a conveyor through letter and package sorters daily.