This interactive dashboard displays AQI data across American states on a choropleth map, with a linked time-series histogram below. The map fills each state with a color from a quantile scale based on its average AQI, while the histogram shows monthly mean AQI values using `d3.bin` and a brush for temporal filtering. Built with React and D3 v5, it uses `geoAlbersUsa` and `geoPath` for map projections and SVG rendering, sourcing data from a CSV of ozone measurements.