A variety of artwork is displayed on the exterior of the building. Sculptor Leo Friedlander used Vermont marble for the large relief sculptures on both sides of the main entrance. One sculpture depicts Meriwether Lewis, William Clark, and Sacagawea, with a map of their expedition's route on the reverse ("Lewis and Clark"); the other ("Covered Wagon") shows pioneers and a covered wagon, with a map of the Oregon Trail on the reverse. Additionally, Ellerhusen created five marble relief sculptures on the exterior, and a metal sculpture by Tom Morandi sits above the south entrance. Ellerhusen also cast six bronze sculptures arranged above the building's main entrance, three on the inside and three on the outside.