After a brief, intensive stint of training in Washington, where he learned to prepare study skins, Ridgway joined the expedition in May. Starting from Sacramento, California, the team explored parts of Nevada, Utah Territory, and Idaho Territory. A highlight of the trip was a stop at Nevada's Pyramid Lake. In the fall of 1868, the members of the team were reduced for funding reasons, but Ridgway returned in 1869 for more work in Utah. In an undertaking that lasted nearly two years, Ridgway collected 1,522 bird-related specimens (753 nests and eggs and 769 skins) and served as a key member on one of the four great surveys of the American West. He observed 262 species, most of these on the western slope of the Sierra Nevada. He had written most of his portion of King's report by 1872, but the "Ornithology" section was not published until 1877. Upon his return to Washington, Ridgway illustrated and wrote for Baird and Thomas M. Brewer's "History of North American Birds" project. He formally joined the Smithsonian in 1874, under the supervision of curator George Brown Goode. In 1880 he received the job title of curator (variously, of ornithology or of the department of birds); he was titled Curator of Birds from 1886 until his death. Working with the institution's collection of approximately fifty thousand bird skins, Ridgway devoted himself to unraveling the taxonomic relationships among North American bird species. As well, he continued his field work to collect new specimens, making several trips to his home state of Illinois, Florida, other states of the U.S., and Costa Rica. The Smithsonian exchanged study skins with other museums, either by donation or loan, and provided material and publications to collectors such as José Castulo Zeledón of the Costa Rican National Museum in exchange for specimens. Ridgway was articulate and literate, and served as the Smithsonian's mouthpiece and representative for many years in the study of birds. He welcomed visits to the museum from colleagues and the general public alike, and would give tours. One of his responsibilities involved assembling public exhibits. In the interest of accessibility, he made books available for browsing and displayed examples of birds described in popular natural histories. As well, he showed birds from well-known poetry, species like the nightingale that are not found in North America. Returning the favor that Baird had paid him, he responded to letters from the public to identify birds and provided artist's materials to a painter in California.