National Dewey Decimal System Day

Celebrated on 12/10/2026

Quick Fact

The Dewey Decimal System, invented by Melvil Dewey in 1876, is used in over 200,000 libraries in at least 135 countries. National Dewey Decimal System Day is celebrated annually on December 10, which coincides with the anniversary of the system's first publication.

Origins and Establishment of National Dewey Decimal System Day

National Dewey Decimal System Day was established to honor the creation of the Dewey Decimal Classification (DDC) system by Melvil Dewey in 1876. Dewey, an American librarian and educator, developed the system to organize library materials by subject, making them easier to find. The day was first observed in 2019, promoted by library organizations and enthusiasts to celebrate the system's enduring impact on information organization.

Evolution and Modern Commemoration

Over time, the DDC has undergone numerous revisions to keep pace with expanding knowledge fields, now in its 23rd edition. National Dewey Decimal System Day is celebrated by libraries, schools, and book lovers through special programs, displays, and social media campaigns. Activities include scavenger hunts using Dewey numbers, trivia contests, and educational events highlighting the system's role in categorizing information.

Facts & General Observations

• The Dewey Decimal System is used in over 200,000 libraries in at least 135 countries worldwide.
• The system has been translated into over 30 languages, with major translations in Arabic, French, German, and Spanish.
• The 000s (Generalities) section includes the most frequently updated categories, such as computer science and internet resources.

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