---
title: "Long-run GDP and population time series for one country"
method: GET
path: "/api/v1/research/maddison/country/{iso3}"
tags: ["Research"]
---

# Long-run GDP and population time series for one country

`GET /api/v1/research/maddison/country/{iso3}`

Returns the full Maddison Project Database time series for one country: GDP per capita in 2011 international dollars (PPP) and population in thousands of people, one row per year from the country's earliest observation to 2022. Country-year cells with no observation return null for both fields (the Maddison panel is 17.8% dense on average - some countries only have data from 1820 onwards, a few Western European cores reach back to year 1 AD). For regional aggregates use `/regional`; for the world aggregate use `/world`. Published under CC BY 4.0 by Bolt and van Zanden at the University of Groningen.

## Path parameters

- `iso3` string, required — ISO 3166-1 alpha-3 country code. Case-insensitive; normalised to uppercase.

## Query parameters

- `start_year` integer, nullable — Inclusive start year (integer). Workbook range is 1 AD through 2022.
- `end_year` integer, nullable — Inclusive end year (integer). Defaults to the latest year in the workbook (2022).

## Response `200`

Year-ordered observations with gdppc (2011 int$) and pop (thousands) plus country metadata.

- EnvelopeMaddisonCountryPayload
  - `data` MaddisonCountryPayload, required — Full long-run time series for one Maddison country.
    - `iso3` string, required — ISO 3166-1 alpha-3 code echoed from the path parameter, uppercased.
    - `country` string, nullable — English country name. Null if the ISO3 is not recognised by the Maddison Project Database.
    - `region` string, nullable — Analytical region the country belongs to in the Maddison Project's 8-region scheme.
    - `region_slug` string, nullable — Slug form of `region`, suitable for `/regional?region=`.
    - `observations` MaddisonCountryObservation[], required — Year-ordered observations for this country. Rows where both `gdppc` and `pop` are null represent country-year cells with no published observation.
      - `year` integer, required — Observation year (Common Era).
      - `gdppc` number, nullable — Real GDP per capita in 2011 international dollars (PPP). Null when not reported.
      - `pop` number, nullable — Mid-year population in thousands of people. Null when not reported.
    - `count` integer, required — Number of observations returned after year-range filtering.
    - `start_year` integer, nullable — Inclusive start year applied, or null if unbounded.
    - `end_year` integer, nullable — Inclusive end year applied, or null if unbounded.
  - `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.
- `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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