This heatmap visualizes the average mathematics GPA for four U.S. states (CA, FL, TX, NY) across multiple years, using a sequential blue color scale. The x-axis represents years, the y-axis lists the selected states, and cell color intensity encodes GPA values. Built with D3 v7 and rendered as SVG, the chart includes axis labels, a color legend, and interactive tooltips that reveal the exact GPA for each state-year pair on hover. The code filters the dataset to focus on four states, making it easy to compare trends over time.