This visualization uses a grouped bar chart to compare job title populations between 1980 and 2023. The code loads data from a merged JSON dataset via `d3.json()` and uses `d3.scaleBand()` for the categorical x-axis, `d3.scaleLinear()` for the y-axis, and SVG `<rect>` elements to render the bars. Hovering over a bar triggers an interactive tooltip that shows the job title and population value. The chart is built with the D3 library (v6) and rendered as static SVG with CSS styling for the legend and tooltip.