A stacked bar chart displays earthquake counts by magnitude range for individual U.S. states across two years. A dropdown menu lets viewers switch between 2017 and 2018, triggering a smooth 750-millisecond transition that updates bar heights, positions, and axis scales. The visualization uses D3 v5 with SVG rendering, employing d3.stack, d3.scaleBand, d3.scaleLinear, and d3.scaleOrdinal to map the year, state, and three magnitude categories from a CSV file. Total counts appear as text labels above each bar.