Nigeria country guide — prepared 24 October 2026

Administrative boundaries, rivers, lakes, marine areas and land mask:
Natural Earth, 1:10m, public domain.
https://www.naturalearthdata.com/about/terms-of-use/
https://github.com/nvkelso/natural-earth-vector/tree/master/geojson
Source files: ne_10m_admin_1_states_provinces.geojson,
ne_10m_rivers_lake_centerlines.geojson, ne_10m_lakes.geojson,
ne_10m_geography_marine_polys.geojson, ne_10m_land.geojson.

The offline snapshot scripts/nigeria-map-source.geojson retains 36 states and
the FCT, with ISO identifiers. Natural Earth's Nassarawa label is corrected to
Nasarawa. Geometry is simplified to 0.001 degrees with topology preserved.
Cities are curated approximate settlement centres, not administrative areas.
Rebuild offline: node scripts/build-nigeria-maps.mjs.

Water features are never clipped to Nigeria or its opening camera. Named
Natural Earth river reaches and lake-centreline reaches are combined, including
the Benue/Bénoué name change in Cameroon. Niger retains its mapped course from
Guinea through Mali and Niger, beside Benin and into the Nigerian delta.
These are complete available generalised source courses, not survey data or
an inventory of every upstream headwater, tributary or delta distributary.

Lake Chad retains the full Natural Earth open-water polygon in Chad/Cameroon.
It depicts a generalised southern open-water pool, not the whole seasonal
lake/wetland basin shared also with Niger and Nigeria, or a current shoreline.
Kainji is a reservoir, not a natural lake. No artificial border clipping is used.

Both bights and the Gulf of Guinea retain their full available mapped extents.
All Natural Earth land is subtracted, including neighbouring countries and
islands. The bights take selection priority over the gulf, so their polygons
are subtracted from the gulf target. Together the marine targets cover the
full source extent. Offshore outlines are hidden. These areas are geographic
learning targets, not maritime claims or navigation boundaries.

Content references:
https://www.britannica.com/place/Nigeria
https://history.state.gov/countries/nigeria
https://www.constituteproject.org/constitution/Nigeria_2011
https://www.worldbank.org/en/country/nigeria/overview
https://whc.unesco.org/en/statesparties/ng/
https://whc.unesco.org/en/list/938/
https://whc.unesco.org/en/list/1118/
https://www.nobelprize.org/prizes/literature/1986/summary/
https://www.wto.org/english/thewto_e/dg_e/dg_e.htm

Photographs: nine existing locally served and individually credited Hausa,
Yoruba and Igbo lesson photographs; two new Wikimedia Commons photographs.
See src/lib/country-guides/nigeria-photos.json for topic credits and the
source sidecars in /images/country-guides/nigeria/ for the new files.