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The encyclopedia · Software & IT · Technical decision · 1966–1971

Library of Congress's MARC made catalogs machine-readable and became the world standard

Henriette Avram's MARC II format let any library exchange catalog records by computer; it became the US national standard in 1971 and MARC 21 worldwide.

Library of Congress

The solution

Through the early 1960s libraries managed their collections with paper cards written by hand and filed in cabinets. As publishing grew, that manual system could not keep up, and the Library of Congress began studying machine-readable cataloging.

The MARC Pilot Project (1966-68) tested distributing Library of Congress cataloging as data on magnetic tape. It led to the MARC II format, designed with a leader, directory, control number and variable fields so it could serve as the standardized communications format for a wide variety of bibliographic data.

The format won by being one neutral structure any computer could read. It became the US national standard in 1971, spread as US MARC, merged with Canada's format into MARC 21 in 1999, and is described as the world's most widely used bibliographic information format — the basis of cooperative cataloging worldwide.

Why it worked

  • One machine-readable record replaced hand-copied catalog cards
  • Free distribution by the Library of Congress seeded every library system
  • Flexible variable fields fit books, music, maps and more
  • Shared records let libraries catalog once and reuse everywhere
What it achievedOne record structure every library system can readclever

What can be applied

If every library would have built its own system, a neutral record format distributed by a trusted keeper makes cooperation possible: standardize the exchange format, and shared cataloging follows.

Aftermath

MARC 21 became the de facto worldwide cataloging standard as national formats migrated to it, enabling cooperative cataloging and global record exchange. The same record structure still underpins most library catalogs and union databases today.

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