A research university's library collection is developed to support the teaching and research needs of its faculty. As such, the collection reflects over a hundred years of changing research interests. Popular culture is a fairly recent area of research, and as such the library's popular culture collections are not as extensive as more established fields of research.

Special collections bring together documents that share some common characteristic, such as rarity, format, subject, or provenance. Rare book libraries and archives are two common types of special collections.

Rare book libraries usually collect published sources, but may also collect manuscripts and other unpublished sources, especially literary manuscripts and manuscripts that relate to the library's rare book collections. Rare book libraries are usually organized like other libraries described in this guide, and are often attached to a research or academic library.

Archives, on the other hand, are organized quite differently than libraries. This difference is due to several factors, including the following:

• The massive quantity of documents acquired by archives (an archive will usually measure the size of its collection by linear feet rather than by number of volumes)
• The special nature of archival collections (which sometimes include access restrictions due to privacy rights of people who are the subjects of the documents)
• The evidentiary value of the collection's arrangement as that arrangement was developed by the collection's original creators and users. 

Unlike library collections, which are organized by subject, archival collections are organized by provenance, and to whatever extent possible the archive will attempt "to maintain the integrity of records in relation to their documentary, provenancial, functional, and jurisdictional contexts",¹ by ensuring that the documents remain organized the way they were organized at the time of their creation, or the time of their accession into the archive.

Other types of documents found in special collections include "maps, games, original works of art, realia (nonbook objects, such as furniture, weaponry, or locks of hair), textiles, audiovisual materials, and digital materials".²

While you will generally use catalogs to discover sources in library collections, you will use finding aids. Finding aids can describe archival collections at different levels of granularity (which depends largely on the ability of archives personnel to process these large collections). A blunt finding aid might simply describe the major record series that compose a collection. A detailed finding aid can describe an archival collection down to the box, folder, or even item level.

The finding aids for archival collections held by the University of Illinois Library are searchable:

Use these databases to identify archival collections held here.

Some examples of special collections (at the University of Illinois Library and elsewhwere) that might be relevant to research on U.S. labor history are listed below. Some of these have been digitized and others would have to be consulted at the Library.