In 1911, Newberry Library Trustee Edward E. Ayer presented to the Library his collection of books, manuscripts, maps, and artifacts about the exploration and settlement of the Americas, the American West, American Indians, the Philippines, and the Hawaiian Islands. Ayer also provided a substantial endowment for the Collection's maintenance and growth. From 1911 until 1963, the Ayer Collection functioned as an independent department and the Ayer Custodians Clara A. Smith, (1911-1931); Ruth Lapham Butler, (1931-1962), and Curator Colton Storm (1962-1963) were responsible for collection administration and acquisitions. In 1963, the Ayer Collection became part of the Special Collections Department, headed by Colton Storm. When Storm retired in 1966, the responsibility for Ayer acquisitions was transferred to bibliographers Frederick Hall and Richard Colles Johnson.

Correspondence, reports, and subject files maintained by Ayer Custodian Ruth Lapham Butler, and her successor, Ayer Curator Colton Storm. Incoming and outgoing curatorial correspondence (Butler, Storm, and Frederick Hall) includes reference requests and letters from librarians, collectors, and scholars (Randolph G. Adams, Lewis Hanke, Henry Raup Wagner, J. C. Wheat, Edith Franklin Wyatt, Charles Eberstadt, Thomas W. Streeter, J. Frank Dobie, Everett D. Graff, Lawrence C. Wroth, Charles McKew Parr). Monthly reports list number of readers, visitors, volumes used and photocopies made; they also describe reader and staff projects and list accessions and gifts. Reports, 1959 1962, also include the Greenlee Collection. Ruth Lapham Butler's subject files contain lists, bibliographies, reports, and correspondence on various Ayer topics including the Philippine Studies Project.

For Ayer Collection correspondence prior to 1934, see the Edward E. Ayer Papers, Record Group 02/15/02.