This example visualizes global population distribution by plotting circular marks for cities on a natural Earth projection. The city points are colored yellow with partial transparency, overlaid on a light gray landmass with graticules and country borders. Built with React and D3 v7, it uses `geoNaturalEarth1` and `geoPath` for the map, a square root scale to map population to circle radius, and loads world atlas TopoJSON and city CSV data via `useWorldAtlas` and `useCities` hooks.