A choropleth map of Florida’s counties uses a Mercator projection fitted to the state’s boundaries, with each county rendered as a gray SVG path. Hovering highlights the county in greenyellow and displays its name in a tooltip. The visualization loads TopoJSON data, converts it to GeoJSON via `topojson.feature`, and projects it with `d3.geoPath` and `d3.geoMercator`. Mouse events (`mouseover`, `mousemove`, `mouseout`) dynamically position and toggle the tooltip’s opacity, while `fitSize` ensures the map fills the viewport.