This example demonstrates how to create a choropleth-style map of the United States using D3.js, highlighting a subset of states with a distinct CSS class. It loads TopoJSON data from `https://d3js.org/us-10m.v1.json` and uses `d3.geoAlbersUsa` for projection and `d3.geoPath` to render state boundaries as SVG paths. The code filters state features against a predefined set of FIPS IDs, though the visual highlighting of selected states is commented out.