US Choropleths Map And Captital/Major Cities
A US choropleth map displays all continental states colored with a white-to-pink linear scale, alongside two city overlays: state capitals as fixed black dots and major cities as population-sized circles. The visualization uses React with d3.geoAlbers projection, d3.geoPath, and d3.geoGraticule to render SVG shapes from US Atlas TopoJSON. City data comes from a world cities CSV and US state capitals JSON. d3.scaleSqrt maps city populations to circle radii.