This visualization shows the geographic spread of confirmed COVID-19 cases across US counties over time, with each county filled according to case counts on a selected date. The map uses an Albers USA projection and renders counties as SVG paths via `d3.geoPath` and TopoJSON. A time slider and play button allow users to animate through the date range, with colors interpolated from a threshold scale using `d3.interpolateReds`. Data comes from a CSV file containing cumulative case counts per county from January to July 2020.