The John Crerar Library is a research library, which after a long history of independent operations, is now operated by the University of Chicago. It is recognized as one of the best libraries in the country for research and teaching in the sciences, medicine, and technology. Throughout its history, the library's technology resources have made it popular with Chicago-area business and industry. Though privately owned and operated, the Library continues to provide free access to the public for the purpose of conducting research in science, medicine and technology. The library opened April 1, 1897, and is named for John Crerar, who first endowed the library, and who gained his wealth by founding a railroad supply firm.
John Crerar died in 1889. His will gave approximately $2.6 million of his estate to Chicago as an endowment for a free public library, selected “to create and sustain a healthy moral and Christian sentiment, and that all nastiness and immorality be excluded.” To comply with Crerar's wishes without duplicating existing area libraries, the directors decided to limit the collections to the sciences, including the history of science. In 1906, the directors expanded the library's mission to include medicine. Since 1951, the collection has focused on current science, technology, and medicine.