This proportional symbol map shows the relative cost of living across US states using colored circles sized by each state’s cost index, with tooltips on hover. The visualization loads US state boundaries from a TopoJSON file via `d3.json` and `topojson.feature`, then plots the CSV data points using `d3.geoAlbersUsa` and `d3.geoPath`. Circle radius and fill color are scaled with `d3.scaleSqrt` and `d3.scaleLinear`, respectively. It uses D3 v7 with SVG rendering, a color legend, and animated opacity and stroke transitions for interactive highlighting.