This interactive choropleth maps U.S. county-level poverty rates from 1980 to 2020, using color intensity to show geographic disparities over time. Built with D3 v7 and TopoJSON, it renders county polygons via `d3.geoPath` and applies a quantizing color scale with `d3.schemeBlues` to encode values. The visualization includes state borders for context and hover titles revealing county names and rates. Poverty data originates from the U.S. Census Bureau's historical tables, with geographic boundaries from a counties-albers-10m TopoJSON file.