The Hertzberg Circus Collection and Museum, a department of the San Antonio Public Library, was established by Harry Hertzberg (1884-1940), a prominent San Antonio lawyer, civic leader, and state senator. One of only a handful of circus collections, it is the oldest public circus collection in the United States and one of the largest in existence. Hertzberg was an avid circus fan who accumulated American circus and related popular-culture memorabilia; he was also a prolific collector of rare books. He bequeathed both of his collections to the San Antonio Public Library, where he had served as member of the board of trustees. His purpose in collecting circus memorabilia was to preserve a record of the history and contributions of the circus to American culture and society; this is the main focus of the museum. In 1942 the San Antonio Public Library formally dedicated the two collections; they were housed in the main building in two new wings added to the third floor to provide space for them. After the dedication the circus collection's size and scope was increased by purchases and donations from circus performers and fans, many of whom were friends of Hertzberg.

When the main library moved to a new location in 1968, the circus exhibits were installed in galleries on the first and second levels of the old library building, which became the library annex. It was more popularly known, however, as the Hertzberg Circus Collection and, later, Museum (Museum was added to the name in the late 1980s). The circus archives and artifacts were housed in separate rooms on the third floor, while the rare books were publicly available in the reading room until the late 1980s. Both the historic building (1930s art deco) and its exhibits are valuable assets to the San Antonio Riverwalk (the Paseo del Rioqv), attracting tourists from all over the world. In addition, researchers from the United States and other countries regularly seek out the circus archives. In 1995 the Circus / Popular Arts Collection and Archives consisted of more than 42,000 items on the American circus during its heyday from the first performance in Philadelphia in 1893 to roughly the late 1930s: artifacts, programs, prints, posters and handbills, photographs, and other memorabilia, as well as sound recordings, sheet music, correspondence, scrapbooks of newspaper and magazine clippings, books, videotapes, magazines and professional journals, and unpublished manuscripts. The strength of the collection lies in the extensive rare poster and photograph holdings. Additional items include World War I posters and Impressionist paintings. Various items from the collection are on display in the exhibit galleries, while the archives are available to researchers by appointment. The museum also houses a specialized library devoted to the American circus and popular culture that contains nearly 3,000 titles, including many rare books. Information about the collections and displays is available through two sources: (1) the illustrated booklet The Inner and Outer Worlds of the Circus: Guide to the Hertzberg Circus Collection (1982), and (2) a video tour of the exhibit areas produced in 1995. The Rare Book Collection contains close to 15,000 volumes in fields such as art, religion, biography, history, costume, and literature. It includes 100 original illuminated manuscripts of Christian and Islamic texts; a leaf of the Gutenberg Bible; a handprinted miniature medieval Bible on vellum (ca. 1250); a numbered, hand-printed copy of Walt Whitman's Leaves of Grass; a numbered and signed copy of A. A. Milne's When We Were Very Young (1924); a first edition in magazine format of Charles Dickens's Little Dorrit (1853); a first edition of Sir Walter Raleigh's History of the World (1614); and signed letters of F. Mendelssohn (1837), Henry Clay (1841), and Emile Zola (1890).

The museum has six areas devoted to permanent exhibits, as well as a temporary exhibits gallery, a special area for children's programming, and a video and library room that is also used for programs and receptions. Some of the more popular items on display include a Gentry Brothers parade and ticket wagon built in 1902; P. T. Barnum memorabilia; Tom Thumb's coach commissioned in 1843 by Barnum; a scale model of a tented circus of the 1920s; and Buffalo Bill's Wild West Show memorabilia. In 1995 there were plans for a major renovation of the building, with access to the Riverwalk, and for new permanent exhibits focusing on Mexican circuses (called las carpas) and on cowboy circuses (such as those of Thomas Edwin Mix and Ken Maynard, as well as Buffalo Bill's Wild West shows). As a division of the San Antonio Public Library System, the Hertzberg Circus Collection and Museum receives support from the City of San Antonio, via the library and the San Antonio Public Library Foundation, and also from admission fees, gift-shop sales, donations, grant requests, and annual fund-raisers. The museum staff holds membership in the American Association of Museums and the Texas Association of Museums. Starting in 1992, with the establishment of two new positions-museum administrator (director) and curator of education-the museum took on new directions in conservation, exhibition, programming, and education. It launched a comprehensive educational program with tours and workshops for schools and learning centers, as well as special events and weekend family programming with puppeteers, storytellers, magicians, and other live performers. In addition, an active series of lectures and presentations in conjunction with temporary exhibits on popular culture reflected a renewed emphasis on the circus as shaping and exemplifying American popular culture, including its multicultural influences. Also, two new performing-arts groups affiliated with the museum-the Hertzberg Puppet Theatre and the Hertzberg Street Theatre Troupe-began offering live entertainment and gallery theater.