This chart shows year-over-year percent population change from 2001 to 2023 for four Massachusetts towns—Hull, Hingham, Scituate, and Cohasset—using grouped bar charts colored by town, with a legend and axes labeled in percentages. It loads data from CSV files via d3.csv in a React component, parses the values in dataLoader.js, and renders with D3 v7 scaleBand and scaleLinear scales, axisBottom and axisLeft, and enter/merge/exit selections to update bars, legend, and axes.