In 1910, the current U. S. National Museum (USNM) opened on the north side of the National Mall. The dinosaur collections were moved across the mall to this new museum, where they have been housed ever since. The mounts of Edmontosaurus and Triceratops were also relocated to become part of the new Hall of Extinct Monsters. There they were joined by new mounts of Ceratosaurus (1910), Camptosaurus (1911), two individuals of Stegosaurus (1913 and 1918), Thescelosaurus (1914), Brachyceratops (1920), and Diplodocus (1931). The Diplodocus skeleton was seventy feet long, and visitors were allowed to walk underneath the skeleton, making it the most popular exhibit for over twenty years.
With Gilmore’s retirement in 1945, the position of Curator of Lower Vertebrates was filled for the first time by a Ph.D. in vertebrate paleontology, Charles Gazin (whose specialty was Cenozoic vertebrates, not dinosaurs). If fact, between 1941 and 2003 the USNM (now the National Museum of Natural History) hired six curators in vertebrate paleontology, none of whom specialized in dinosaurs.
One of these curators, Nicholas Hotton III, undertook the first major renovation of the dinosaur hall in the early 1960s. This hall utilized all the existing mounts and added one more, the specimen of Gorgosaurus (completed in 1960) currently exhibited on the north wall. Although most of the dinosaur skeletons were unchanged, the hall itself was substantially redesigned and reorganized. This hall opened to the public in 1963, and while the visiting public was no longer allowed to walk under the Diplodocus, there was now a sauropod femur that they were allowed to touch.
The hall closed again in 1979 as planning began for a new hall that would highlight the museum’s collections as part of “Fossils: The History of Life”. Again, all of the existing dinosaur mounts were kept, but rearranged to suit the new design of the exhibit. One new mount, Allosaurus, was constructed and integrated into a central exhibit of Late Jurassic dinosaurs. This new hall was opened in December,1981, and remains the centerpiece of the Smithsonian’s paleontology exhibit.