This visualization displays SO2 emissions across 31 U.S. states from 2012 to 2021, using a horizontal bar chart that animates through each year when a button is clicked. The chart encodes emission values with bar lengths, mapping data through d3.scaleLinear for the x-axis and d3.scaleBand for the categorical state labels. Rendered as an SVG with D3 v6, the visualization uses a radio button to trigger the animation, presenting yearly snapshots of pollution data in a compact, color-coded format.