This choropleth map displays poverty estimates for US counties in 2021, with each county shaded according to its poverty rate using a blue sequential color scale and a legend with tick marks. The visualization also includes state boundary outlines overlaid on the county polygons. Built with D3 v5, the map uses `d3.json` to load TopoJSON data from the us-atlas collection and `d3.csv` to parse county-level poverty rates, then renders the geography via `d3.geoPath` and `topojson.feature`. The color encoding applies `d3.scaleThreshold` and `d3.schemeBlues`, while an axis legend is generated with `d3.axisBottom`.