Fork of world map w/ cities & countries pop!
This visualization displays a world map with cities over 50,000 population, using circles scaled by population size and country polygons colored by opacity to reflect national population. The map uses `d3.geoNaturalEarth1` projection with `d3.geoPath` to render land, graticules, and geographic lines, while React manages the component state. City data comes from Simplemaps, country boundaries from World Atlas TopoJSON, and population figures from UN 2019 estimates. Tooltips show city populations and country names, with missing country data marked as “no data.”