This D3.js bar chart visualizes COVID-19 case totals for fifteen U.S. states, sourced from a CSV file fetched via `d3.csv`. The horizontal bars, rendered as SVG rectangles, are scaled with `d3.scaleBand` and `d3.scaleLinear` based on the maximum case count. The chart includes gridlines and axis tick labels generated through custom mapping functions, and is built within a React component using `useState` and `useEffect` hooks, with styling applied via inline attributes.