A grouped and stacked bar chart displays earthquake counts by magnitude range across US states for 2017 and 2018. A dropdown menu switches between years, animating bar heights and total labels with 750-millisecond transitions. Built with D3 v5, the visualization uses `d3.csv` to load data, `d3.stack` to create layers, and `d3.scaleBand`, `d3.scaleLinear`, and `d3.scaleOrdinal` for axes and color encoding. SVG transitions update the chart smoothly when the selected year changes.