---
title: "Historical AIS vessel-density grid (US, months-lagged analytics)"
method: GET
path: "/api/v1/maritime/history/density"
tags: ["Global Economy & Trade"]
deprecated: true
---

# Historical AIS vessel-density grid (US, months-lagged analytics)

`GET /api/v1/maritime/history/density`

> **Deprecated.**

Coarse vessel-density grid folded from NOAA MarineCadastre daily AIS files. Historical analytics, months-lagged - NOT live and NOT a current snapshot. Coverage is United States historical analytics. Each grid cell carries a vessel observation count and an AIS ship-type breakdown. Optional bbox filters cells; optional date reads a specific day's shard (defaults to the latest folded day). Source: NOAA / BOEM MarineCadastre (public domain, CC0).

## Query parameters

- `bbox` string — Bounding box 'minLon,minLat,maxLon,maxLat' to filter grid cells.
- `date` string — ISO date YYYY-MM-DD; defaults to the latest folded day.

## Response `200`

Coarse historical vessel-density grid with CC0 attribution and a months-lagged honesty note.

- EnvelopeAisHistoryDensityData
  - `data` AisHistoryDensityData, required — Payload for GET /maritime/history/density. Historical analytics, months-lagged - NOT live positions. Sourced from the NOAA / BOEM MarineCadastre public-domain (CC0) daily AIS files, folded into a coarse density grid at ingest.
    - `coverage_label` string — Honest coverage label - US historical analytics, never global live.
    - `as_of_date` string, required — source_file_date of the NOAA daily file folded (YYYY-MM-DD).
    - `lag_note` string — Honesty label - the NOAA source itself lags the calendar by months.
    - `grid` AisGridCell[], required — Coarse density grid cells (bbox-filtered when bbox given).
      - `lat_bin` number, required — Rounded latitude bin (cell_resolution_deg).
      - `lon_bin` number, required — Rounded longitude bin.
      - `vessel_count` integer, required — Observations folded into this cell.
      - `by_ship_type` object — {ais_ship_type_code: count} breakdown for this cell.
    - `sources` AisAttribution[], required — Provenance - NOAA CC0 attribution.
      - `source` string, required — Human-readable source label.
      - `license` string, required — License short name.
      - `license_url` string, required — Canonical license deed URL.
      - `attribution_text` string, required — Exact credit string to surface.
      - `modified` boolean, required — True when Sugra transforms the data.
      - `original_url` string, required — Link back to the upstream source page.
    - `stale` boolean, required — True when the BLOB write (not the data) is older than 2h.
  - `meta` SugraMeta, required — Metadata attached to every /api/v1/* response envelope.
    - `endpoint` string, required — Requested endpoint path.
    - `data_time` string, required — ISO 8601 UTC timestamp of the source data, not of the request.
    - `response_time` string, required — ISO 8601 UTC timestamp when this response was produced.
    - `provider` string, required — API name and version.
    - `source` string, nullable — Identifier of the primary upstream source used for this response.
    - `attribution` string, nullable — Human-readable attribution mandated by an upstream source (e.g. a securities regulator or self-regulatory organization). Present only on responses whose source requires the owner and source to be clearly identified. Do not remove or alter it when using the response.
    - `fallback_used` boolean, nullable — True when the primary source failed and a fallback produced the data.
    - `fallback_chain` string[], nullable — Ordered list of sources attempted, in the order they were tried.
    - `cached` boolean, nullable — True when this response was served from the internal cache.
    - `stale` boolean, nullable — True when the cached response was returned after the upstream rate-limited or errored. Clients can use this to detect degraded data.

## Other responses

- `401` — Missing or invalid `x-api-key` header. JSON body with a stable `code` distinguishing `missing_api_key` (no header sent) from `invalid_api_key` (header sent, key not accepted); any other 401 source carries the generic `unauthorized` with its detail as `reason`. Plus `hint`. `plan` is always null on 401 - an unauthenticated request has no plan; quota exhaustion is 429, not 401.
- `422` — Validation Error
- `429` — Daily rate limit exceeded. Check `X-RateLimit-Reset` for the next window.
- `503` — Upstream source is temporarily unavailable. Retry after a short delay.

---

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