Sized Points on a Map
A world map displays cities with populations exceeding 50,000, using sized points to encode population via a d3.scaleSqrt square-root scale. The visualization renders a Natural Earth projection using d3.geoNaturalEarth1 and d3.geoPath, with graticules and country boundaries from World Atlas TopoJSON. City data from Simplemaps is plotted as semi-transparent circles. The React-based code loads TopoJSON and CSV data asynchronously, then applies d3.geoPath to project coordinates and d3.scaleSqrt to determine circle radii.