A stacked bar chart displays H1-B visa petition numbers across states, where each bar’s stacked segments represent distinct immigration program categories from the Office of Foreign Labor Certification data. Hovering over a legend entry filters the chart, highlighting only the selected program’s bars while dimming others. Built with D3.js, the visualization uses `d3.legend.color`, `d3.layout.stack`, and `d3.tip` for interactive tooltips, rendered as an animated SVG. The x-axis shows petition counts, while the y-axis lists states, encoded via `d3.scale.ordinal`.