Library of Congress Classification to JSON

lcc2json outputs a single JSON file of the Library of Congress Classification system.

For input, it downloads 699 .json files, 14 megabytes in total, from the Library of Congress.

Install

Install from PyPI:

pip install lcc2json

Or install from main source repo, such as:

git clone https://spacecruft.org/books/lcc2json
cd lcc2json/
python -m venv venv
source venv/bin/activate
pip install -U setuptools pip wheel
pip install -e .

Usage

Thusly.

Download the source JSON files from the Library of Congress

lcc2json-dl

Parse the downloaded JSON files and output a single JSON file:

lcc2json

Help

Download script help:

(venv) jebba@rs-pencil:~/devel/spacecruft/books/lcc2json$ lcc2json-dl --help
usage: lcc2json-dl [-h] [-o OUTPUT_DIR] [-d MAX_DEPTH] [-v] [--dry-run]

Download Library of Congress Classification JSON files from id.loc.gov

options:
  -h, --help            show this help message and exit
  -o, --output-dir OUTPUT_DIR
                        Output directory for JSON files (default: json)
  -d, --max-depth MAX_DEPTH
                        Maximum depth to crawl (default: 2)
  -v, --verbose         Enable verbose logging
  --dry-run             Show what would be downloaded without actually downloading

Examples:
  lcc2json-dl                     # Download all classifications to ./json/ (depth 2)
  lcc2json-dl --max-depth 4       # Download to depth 4 (includes subdivisions)
  lcc2json-dl -o lcc_data         # Download to ./lcc_data/
  lcc2json-dl -v                  # Verbose output
  lcc2json-dl --dry-run           # Show what would be downloaded

Depth levels:
  0 = Root classification scheme
  1 = Main classes (A-Z)
  2 = Subclass ranges (e.g., PR1-PR9680) [default]
  3 = Period/topic divisions (e.g., PR6050-PR6076)
  4 = Alphabetical ranges (e.g., PR6066.A-PR6066.Z)
  5+ = Individual entries (e.g., PR6066.A84)

Output JSON script help:

$ lcc2json --help
usage: lcc2json [-h] [-i INPUT_DIR] [-o OUTPUT] [-v] [--ranges]

Extract LCC outlines from downloaded JSON files.

options:
  -h, --help            show this help message and exit
  -i, --input-dir INPUT_DIR
                        Directory containing JSON files (default: json)
  -o, --output OUTPUT   Output file path (default: lcc.json)
  -v, --verbose         Enable verbose output
  --ranges              Include start/stop/prefix range fields in output (larger file size)

JSON Data

Depth 1

• 21 files.
• ~5 second download.
• 215K size.
• 21 classification entries.

Depth 2

• 698 files.
• 2 minute download.
• 14M size.
• 14,786 classification entries.
• 516 unique prefixes.

Depth 3

• 14,581 files.
• 2 hour download.
• 161M size.
• 101,699 classification entries.

Depth 4

• 100,551 files.
• 14 hour download.
• 824M size.
• 344,073 classification entries.
• Two missing (404) files.

Depth 5

• 342,499 files.
• 2 day download.
• 2.9G size.
• 766,892 classification entries.
• Three missing files.

Depth 6

• 765,185 files.
• 5 day download.
• 5.7G size.
• Eight missing files.

Depth 7

• 1,311,227 files.
• 10 day download.
• 8.8G size.
• 31 missing files.

Downloads

JSON data snapshots are also available at this URL, so, optionally you don't have to download with this script:

• https://spacecruft.org/books/lcc2json-data

📄 License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.

Copyright © 2025 Jeff Moe