This map visualization displays global city populations as proportional circles overlaid on a world map with country boundaries, graticules, and interior borders. The map uses a Natural Earth projection, with data sourced from the World Atlas TopoJSON and a clean CSV of world cities. Built with React and D3 v5, the code leverages `d3.geoNaturalEarth1`, `d3.geoPath`, and `d3.geoGraticule` for the geographic elements, while `d3.scaleSqrt` maps population values to circle radii. The SVG rendering is styled with a cohesive gray and teal palette.