- Categories:
- Fun
- Tags:
- Books
- Where:
- United States
- Date change rule:
- Every December 10
- Holiday emoji:
- 📚
Dewey Decimal System Day celebrates Melvil Dewey and his groundbreaking library classification system every December 10. This ingenious method organizes knowledge, making it easier for millions to find books in libraries worldwide. Explore the system, visit your local library, and appreciate the order it brings to our literary world.
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History of Dewey Decimal System Day
Melvil Dewey, the creator of the famed Dewey Decimal System which classifies mostly non-fiction library books and resources, was born on December 10, 1851, in New York and this date has been adopted to celebrate and honor him annually for Dewey Decimal System Day.
Dewey created his proprietary system of library resource classification while working at the Amherst College library at the age of 21. The Dewey Decimal System was first published in 1876 and is now the most widely used system around the world in over 200,000 libraries in 135 countries. The 20th edition of the system had been published by the late 20th century.
The system allows us to locate resources by topic assigned to one of 10 classes. The 10 main groups are 000–099, general works; 100–199, philosophy and psychology; 200–299, religion; 300–399, social sciences; 400–499, language; 500–599, natural sciences and mathematics; 600–699, technology; 700–799, the arts; 800–899, literature and rhetoric; and 900–999, history, biography, and geography.
Each class is further categorized into 10 hierarchical divisions which are then subcategorized into 10 sections. The Dewey system’s numerical classification provides a shorthand identification and location tool. The notation lends itself to memory through the constant repetition of a standard pattern — area arrangement, different numbers for particular languages — through parallel subject developments and patterned repetition of standard subdivisions, such as theory, history, geography and so on.
It’s hard to believe it’s been over 100 years since the original introduction of the Dewey Decimal System. Today, Americans check out an average of 7 items from their local libraries every year so the need to maintain order continues. The digital age made the beautiful card catalog cabinets housing the index cards listing the decimal classification obsolete. Interestingly, Dewey also helped to create the index cards themselves. The same year he created the decimal system, Dewey founded the Library Bureau, a company selling index cards and filing cabinets.
Dewey Decimal System Day timeline
The first US library is established for and by African-Americans in Philadelphia.
While the first vision for a national library was suggested in 1556 in the UK, the idea did not take off until 1753 when one opened to the public as part of the British Museum.
Zenodotus is the first librarian recorded in history at the Library of Alexandria in Egypt, which was one of the largest and most significant libraries of the ancient world until it was believed to be burnt down.
The Library of Ashurbanipal in Iraq is believed to be one of the oldest libraries in the world.
Dewey Decimal System Day FAQs
When is Dewey Decimal System Day?
Dewey Decimal System Day 2026 falls on Thursday, December 10. It’s a perfect day to appreciate the structured world of libraries and the genius behind their organization.
How many books are organized by the Dewey Decimal System?
The Dewey Decimal System is used in over 135 countries and in more than 200,000 libraries worldwide. While an exact number of books isn’t available, it’s safe to say billions of items are classified by this system.
How many public libraries are there in the U.S.?
According to the Institute of Museum and Library Services, there are approximately 9,000 public libraries in the United States. These libraries serve nearly all communities across the nation.
What are the main categories of the Dewey Decimal System?
The Dewey Decimal System divides all knowledge into ten main classes, from 000 (Computer Science, Information & General Works) to 900 (History, Geography & Auxiliary Disciplines). Each class is further subdivided for granular organization.
How To Celebrate Dewey Decimal System Day
Visit your local library
See the Dewey Decimal System in action at your local library. Ask one of the librarians for their opinion on how efficient the system is and how many questions they get every day about it when helping patrons find books.
Take the Dewey Decimal Challenge
Read one book from each of the 10 Dewey Decimal categories. This is like a book club on steroids! Invite your book club members or general friends to read along.
Plan a stay at the Library Hotel
The Library Hotel in Midtown Manhattan, New York is a boutique hotel themed around the Dewey Decimal System. Each of its 10 guest floors is linked to one of the 10 Dewey Decimal categories with anywhere from 50 – 150 books in each room with over 6,000 throughout the entire hotel. Yes, you can request a particular category for your stay.
5 Amazing Facts About Global Libraries
The Old Library
One of the most beautiful libraries in the world, the Long Room of the Old Library in Dublin, Ireland’s Trinity College has been a working library since 1732.
Library of perfumes
Instead of old, musty smelling books, the Osmotheque, in Versailles, France, is a library of perfumes with over 3,000 scents.
The Vatican Apostolic Archive
Created by Pope Paul V in 1612, the Vatican Secret (now, Apostolic) Archive contains the private, papal collection of documents such as correspondence and account books or records.
Magical reads
The Conjuring Arts Research Center, a library dedicated to magic, tricks and related topics, opened in Manhattan, New York in 2003.
Bats to the rescue
A colony of bats resides in the Rococo Library in Portugal, so while the library is closed at night, the bats eat book-damaging bugs!
Why We Love The Dewey Decimal System
We love to be organized
Sure, the OCD world thanks Dewey for helping us with our preoccupation with order and exactness but even those who struggle with alphabetizing couldn’t get around a library without the help of his classification system. Who doesn’t love bringing a little order to chaos?
We love a good treasure hunt
If simply desiring order isn’t your thing, perhaps it’s the thrill of the hunt! If you need to entertain kids — or adults — for a day, pretend you are searching buried treasure and see who can find the books you need fastest!
We love consistency
Used in over 135 countries around the world, the Dewey Decimal System has brought consistency to libraries globally. The Arabic numerical system it uses is commonly understood across cultures.
Dewey Decimal System Day dates
| Year | Date | Day |
|---|---|---|
| 2026 | December 10 | Thursday |
| 2027 | December 10 | Friday |
| 2028 | December 10 | Sunday |
| 2029 | December 10 | Monday |
| 2030 | December 10 | Tuesday |
