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, in the API Commons Rate Limits shape.

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

Limit state is signalled in the retryAfter response header, and an exhausted limit returns HTTP 429.

This profile was written by API Evangelist and has not been verified against a page the provider published; treat every limit as unconfirmed until a dated transcription replaces it.

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

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

3 Limits Exhausted: HTTP 429 retryAfter
Method: generated, dated 2026-06-13.
Written by API Evangelist on 2026-06-13 and not verified against a page the provider published. Treat every limit as unconfirmed until a dated transcription replaces it.
View Source
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.

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  • 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.
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Call it yourself

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

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