This example displays a choropleth-style map of Massachusetts where each circle’s radius encodes the crime-to-population ratio, allowing quick comparison of crime rates across counties. The map uses a `geoAlbers` projection with `geoPath` to render the state boundary, while circles are positioned via `projection` and sized with `scaleSqrt`. Data comes from a CSV file and a TopoJSON file, loaded using `d3.csv` and `d3.json`. The visualization is built with React and D3 v5, rendering in SVG.