This stacked bar chart displays population data for cities, grouped by state and country. It uses D3.js v6 to process the nested dataset with `d3.nest()` and `d3.stack()`, then renders the stacks as SVG rectangles with an ordinal color scale. The chart includes axes via `d3.axisBottom()` and a legend. The data is hardcoded in the script rather than loaded from an external source.