The complete Library of Congress Classification as used in Shelvd — every class, subclass, and range, with context for the collector who encounters LCC numbers in catalog records and wonders what they mean.
The Library That Outgrew Dewey
When the Library of Congress moved into its new building in 1897, its librarian Herbert Putnam faced a problem: Melvil Dewey's decimal system, elegant as it was, couldn't handle a collection that was already the largest in the Western Hemisphere and growing by the trainload. The ten main classes were too rigid. The decimal subdivisions were getting absurdly long. And the Library of Congress needed something designed for their shelves, not for the public libraries Dewey had in mind.
So they built their own system. Where Dewey used numbers, LCC used letters — giving it 26 possible main classes instead of 10. Where Dewey extended with decimals, LCC extended with numbers and further letters, creating a flexible alphanumeric system that could grow without breaking.
The result is sprawling, occasionally inconsistent, and unmistakably American in its assumptions — but it works. It has worked for over a century, and it now classifies over 175 million items.
How It Works
An LCC call number has two parts: the classification number (what the book is about) and the Cutter number (which specific book it is).
PR6039.O32 G6 1954
│││ │ │
│││ │ └── Year
│││ └──────── Cutter for title (The Lord of the Rings)
││└───────────────── Cutter for author (Tolkien)
│└────────────────── Subclass number range (1900–1960)
└─────────────────── Class/Subclass (PR = English literature)
The letters at the beginning are the key. One letter is a main class; two letters is a subclass. After that come numbers (sometimes with decimals) that narrow the subject further. The Cutter number — that decimal-point-plus-letters bit — identifies the specific work.
The 21 Main Classes
| Letter | Subject | Subclasses |
|---|---|---|
| A | General Works | AC, AE, AG, AI, AM, AN, AP, AS, AY, AZ |
| B | Philosophy, Psychology, Religion | B, BC, BD, BF, BH, BJ, BL, BM, BP, BQ, BR, BS, BT, BV, BX |
| C | Auxiliary Sciences of History | CB, CC, CD, CE, CJ, CN, CR, CS, CT |
| D | World History (except Americas) | D, DA, DAW, DB, DC, DD, DE, DF, DG, DH, DJ, DJK, DK, DL, DP, DQ, DR, DS, DT, DU, DX |
| E | History of the Americas | E (single class, no subclasses) |
| F | History of the Americas (Local) | F (single class, no subclasses) |
| G | Geography, Anthropology, Recreation | G, GA, GB, GC, GE, GF, GN, GR, GT, GV |
| H | Social Sciences | H, HA, HB, HC, HD, HE, HF, HG, HJ, HM, HN, HQ, HS, HT, HV, HX |
| J | Political Science | J, JA, JC, JF, JJ, JK, JL, JN, JQ, JS, JV, JX, JZ |
| K | Law | K, KB, KBM, KBP, KBQ, KBR, KBU, KD, KDC, KDK, KDZ, KE, KF, KG, KH, KJ, KJV, KK, KL, KN, KP, KQ, KZ |
| L | Education | L, LA, LB, LC, LD, LE, LF, LG, LH, LJ, LT |
| M | Music | M, ML, MT |
| N | Fine Arts | N, NA, NB, NC, ND, NE, NK, NX |
| P | Language and Literature | P, PA, PB, PC, PD, PE, PF, PG, PH, PJ, PK, PL, PM, PN, PQ, PR, PS, PT, PZ |
| Q | Science | Q, QA, QB, QC, QD, QE, QH, QK, QL, QM, QP, QR |
| R | Medicine | R, RA, RB, RC, RD, RE, RF, RG, RJ, RK, RL, RM, RS, RT, RV, RX, RZ |
| S | Agriculture | S, SB, SD, SF, SH, SK |
| T | Technology | T, TA, TC, TD, TE, TF, TG, TH, TJ, TK, TL, TN, TP, TR, TS, TT, TX |
| U | Military Science | U, UA, UB, UC, UD, UE, UF, UG, UH |
| V | Naval Science | V, VA, VB, VC, VD, VE, VF, VG, VK, VM |
| Z | Bibliography, Library Science | Z, ZA |
You'll notice there is no I, O, W, X, or Y. These were reserved for future use. Over a century later, they're still unused — proof that even the most ambitious classification system can overestimate the pace of human knowledge production.
Why Collectors Should Care
LCC numbers appear less frequently than DDC on copyright pages, but they dominate academic library catalogs. If you're looking up a book in the Library of Congress, Harvard, or any major research library, the call number you'll see is LCC.
For collectors, LCC is useful because:
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Precision — LCC can express finer distinctions than DDC. Where DDC puts all English fiction in 823, LCC distributes it across PR1–PR9680, with separate ranges for medieval, Elizabethan, Restoration, Georgian, Victorian, and modern periods — and individual Cutter numbers for specific authors.
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Academic context — LCC tells you how the scholarly world classifies your book. A first edition of The Great Gatsby is PS3511.I9 G7 — which places it in American literature (PS), authors beginning with F (3511), Fitzgerald (.I9), and Gatsby (G7). That string of characters connects your book to every other copy in every research library in America.
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Enrichment — When Library Lookup returns an LCC code, Shelvd resolves it. "PR" becomes "English literature." "QA" becomes "Mathematics." This saves you from having to memorize 497 subclass codes.
In Shelvd
The LCC field lives in the Subject Classification section. Shelvd contains 8,253 LCC entries — every class, subclass, and range from the Library of Congress Classification Outline. Type a code and see its description; type a description and see matching codes.
The data was extracted from the publicly available LoC Classification Outlines (public domain) and covers the full depth of the published schedules: from "A — General Works" down to ranges like "PR1490–PR1799 — 17th and 18th centuries (1640–1770)."
Key Subclasses for Book Collectors
Some subclasses are particularly relevant if you collect books:
| Subclass | Subject | Why it matters |
|---|---|---|
| PR | English literature | The home of Shakespeare (PR2750–PR2772), Dickens, Austen, Tolkien |
| PS | American literature | Melville, Hemingway, Fitzgerald, Faulkner |
| PQ | French, Italian, Spanish, Portuguese literature | Proust, Dante, Cervantes, Camões |
| PT | German, Dutch, Scandinavian literature | Goethe, Kafka, Ibsen |
| Z | Bibliography, Library Science | Books about books — where collectors live |
| Z1001–Z8999 | National and subject bibliography | Bibliographies by country and topic |
| N–NX | Fine Arts | Illustrated books, art monographs, exhibition catalogs |
| ND | Painting | Art books, catalogues raisonnés |
| QA | Mathematics | Early printed science, Newton, Euclid |
| BX | Christian denominations | Early printed theology, Bibles, liturgical works |
Shelvd's LCC reference table contains 8,253 entries across 497 subclasses. During editing, the LCC field provides bidirectional search — type a class code or a subject description, and Shelvd resolves the other.