POPULATION SPLIT

Real people. Open data.

The numbers behind the game come from open population data. Here’s what they represent and how we turn them into a playable map.

Population estimates: GHSL 2020

Population: Schiavina M., Freire S., Carioli A., MacManus K. (2023), GHS-POP R2023A — GHS population grid multitemporal (1975–2030), European Commission, Joint Research Centre. We use the 2020 epoch of the WGS84 30-arcsecond grid, approximately 1 km at the equator.

Dataset documentation · Dataset DOI · CC BY 4.0 license

The game grids are adapted subsets: cropped to their displayed regions, masked by country boundaries, summed into larger cells and rounded. The source includes both urban and rural residential population. These are modelled estimates for 2020, rather than a live population count.

Maps and place names

Country outlines and city locations come from Natural Earth at 1:10 million scale, used under its public domain terms. Boundaries follow that dataset’s de facto representation. Nearby countries are shown for context; only the coloured country’s population counts toward a round.

Explore: controlled randomness

Explore starts from 60 geographic windows across six inhabited continents. Each round generates a new grid-aligned crop inside one of those windows. Its seed determines the exact framing, so daily puzzles and friend challenges reproduce the same maps. Five-round Explore journeys span different continents.

Candidates are checked for population, populated-cell count, land coverage and concentration. Island windows use a suitable land-coverage threshold. Crops that are overwhelmingly empty or dominated by one population cell are rejected. Only people within the outlined rectangle count; the window may cross country borders. Lakes and ocean areas remain uncoloured. A crop keeps complete source cells, preserving their summed population.

States, counties, provinces and territories

Search for a named area or play a random one. Random UK journeys skip areas with fewer than 20 populated source cells; those small areas remain available through search. US States includes 50 states and Washington, DC. Australian States & Territories includes six states, the Northern Territory and the Australian Capital Territory. Canadian Provinces & Territories includes ten provinces and three territories. These boundaries come from Natural Earth Admin 1; exact included islands and exclusions are described with each map.

UK Counties uses the official ONS December 2025 Counties and Unitary Authorities geography: 218 areas covering all four UK nations. These include English counties, unitary authorities, metropolitan districts and London boroughs/City, Welsh unitary authorities, Scottish council areas, and Northern Ireland local government districts. “Counties” is the mode’s umbrella label. They are not historic counties. The population data still represents 2020.

Source: Office for National Statistics licensed under the Open Government Licence v.3.0. Contains OS data © Crown copyright and database right 2025. ONS licensing · Open Government Licence v3.0.

How your score works

We calculate the population on each side of your line. Each grid cell that the line crosses contributes proportionally to the area of that cell on each side. The population inside each aggregate cell is treated as evenly distributed. A perfect 50/50 split earns 100 points. Each percentage point away from 50 removes two points: a 55/45 split earns 90, and 70/30 earns 60.

The dashed green comparison line keeps your angle and slides to a population balance. It shows one balanced split; many different angles can also divide a country equally.

Resolution and accuracy

To keep the game fast, country maps use cells roughly 4–26 km across. Small counties and boroughs retain the native grid at approximately 1 km, while larger subdivisions and Explore windows use aggregated cells. Very small areas, such as the City of London, contain only a few source cells and have a coarser effective scoring resolution. We preserve the population total while aggregating. Source modelling, boundary choices, omitted islands and the within-cell approximation affect the result. The population shown can differ from official national totals, especially where the game covers a mainland or excludes remote territories.

What each map includes

US States coverage

51 maps.

UK Counties coverage

218 maps.

Australian States & Territories coverage

8 maps.

Canadian Provinces & Territories coverage

13 maps.

Reproducibility

Source URLs and file hashes and the map catalog are available. Population source access began on 16 October 2026; new mode datasets were prepared on 17 October 2026. Each mode has its own catalog, exact source URLs and processing notes: Explore · US States · UK Counties · Australian States & Territories · Canadian Provinces & Territories. See the full methodology and data contract.