Chronicling America · Rate Limits

Chroniclingamerica Rate Limits

Rate limit profile for the Chronicling America API. The Library of Congress enforces rate limits across all chroniclingamerica.loc.gov endpoints to ensure equitable public access. No authentication or API key is required, so limits are applied per IP address. Exceeding limits typically results in a temporary block or HTTP 429 response. Implementers should apply exponential backoff and respect Retry-After headers.

Chroniclingamerica Rate Limits is the machine-readable rate-limit profile for Chronicling America on the APIs.io network, conforming to the API Commons Rate Limits specification.

It captures 3 rate-limit definitions, across the free tier, measuring requests_per_minute.

The profile also includes response codes documented for throttled and serviceUnavailable.

Tagged areas include Newspapers, Historical, Archives, Library of Congress, and Government.

3 Limits Throttle: 429
NewspapersHistoricalArchivesLibrary of CongressGovernmentRate LimitingThrottling

Limits

Search and Metadata Endpoints ip
requests_per_minute · minute
150
Applies to /search/pages/results/, /newspapers.json, /lccn/{lccn}.json, /lccn/{lccn}/issues.json, /batches.json, and /batches/{batch_name}.json endpoints. Sustained crawling above this rate may trigger a 1-hour IP block.
Page and OCR Text Endpoints ip
requests_per_minute · minute
150
Applies to /lccn/{lccn}/{date}/ed-{edition}/seq-{sequence}/ page endpoints and .txt OCR text files. The same 150 req/min guideline applies. For bulk OCR harvest, LOC Labs provides pre-built bulk OCR data downloads that avoid API rate limits entirely.
Image and Binary File Downloads ip
requests_per_minute · minute
60
Applies to JP2, PDF, and TIFF image file downloads from storage. Large image files (JP2/TIFF can be 5–30 MB per page) place significant load on storage services; a lower rate is recommended. Download only the format needed; JP2 is suitable for most digital-humanities use cases.

Work with this as data

Every rate limit here is available over the APIs.io API and to AI agents over MCP.

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Tools for rate limits

4 MCP tools reach this
  • find_rate_limitsBrowse and filter every rate limit in the catalog.
  • apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
  • resolveTurn a domain, URL or GitHub org into the provider it belongs to.
  • find_cohortsEvery scored population of providers in the catalog.
All 92 tools →

Call it yourself

curl for this page
This rate limit 
curl "https://apis.io/api/v1/rate-limits/chroniclingamerica-rate-limits"
All rate limits 
curl "https://apis.io/api/v1/rate-limits?limit=25"

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