By a curious coincidence, I just noticed that the earliest surviving entries in the LCSH Subjects files were created on January 27th, 1986. This date would have been the first Monday after the ALA Midwinter conference (Jan 18th-22nd ,1986).

From the time stamps, it seems as if the system became live for new entries on this date. Older entries weren’t added until Feb 11th.

Less than half of these converted entries have had their references evaluated. This is suggestive.

Reference evaluation (008/29)

Value Count Percentage
a (Evaluated) 45,495 38%
b (Not Evaluated) 46,387 39%
n (No References) 27,320 23%
Total 119,202 100%

[LCSH 150s, established, as obtained from authorities.loc.gov of December 2006]
Simon
p.s.
The oldest surviving record, for “Grouper fisheries”, was assigned LCCN “sh 86000005″.
You should have seen the ones that got away.

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