It is with pleasure that the Cataloging Policy and Support Office announces that the subject authority file has reached a milestone. At the end of February 2007 there were 300,065 subject authority records, making it by far the largest subject authority file in the world.
There was a time when this number seemed inconceivable. For instance in August of 1947 there were 60,000 subject authorities on individual 3x5 cards. In 1986 the file of subject authority data that had been maintained on an Administrative Terminal System was converted to 150,093 individual subject authority records in MUMS. Then in August of 1999 when the Library converted to the Voyager ILS there were 249,182 subject authority records on file. At that time copies of each valid subject authority record were made in order to create a separate and secure master file of subject authority records from which all subject authority products are produced.
New subject authority records and proposed changes to existing subject authorities are made in the regular Voyager database ( LCDB). Copies of these proposals are migrated to the LCSH Master file and are prepared by Subject Headings Editorial staff for inclusion on weekly lists, which is the vehicle for conveying proposals to the editorial process. New subject authority records added annually has remained at a relatively stable rate of 6,000-8,000 records.