This example shows a choropleth map of US states with an interactive slider that filters states by population, highlighting those above a threshold in steelblue while leaving others lightgray. The map uses D3 v7’s `d3.geoAlbersUsa` projection and `d3.geoPath` to render TopoJSON state boundaries from `us-10m.v1.json`. Population data loads from a local CSV file, and the slider triggers a filter function that updates the fill colors. The visualization also includes a legend showing the current filter percentage.