A line chart depicts COVID-19 cases and deaths in the US over time. Two smooth, animated curves, one red and one blue, trace these metrics, with axes for dates and population counts. Built with React, D3 v4, and SVG, it uses `d3.line`, `d3.curveMonotoneX`, and `d3.transition` for drawing. Data comes from a CSV file, which is loaded via `d3.csv`.