The collection primarily consists of postmarked envelopes, postcards, and correspondence that Bilyeu organized in albums. The albums included postmarked envelopes from all 36 Oregon counties as well as Portland, Oregon; postcards, stationery, and other material relating to the 1905 Lewis and Clark Centennial Exposition in Portland; and to railroad lines. The collection also includes books, catalogs, scholarly articles, and other loose materials that Bilyeu possessed.