This visualization displays the US population by age, sex, and year from 1850 to 2000, using grouped bars to compare age cohorts over time. Built with the Vega-Lite API, it encodes year on the x-axis, population counts on the y-axis, and age groups as color, with tooltips revealing sex and population values. The code loads CSV data via `d3.csv` from a GitHub gist, configures axes and label styling through the `config` object, and renders the chart using the Vega, Vega-Lite, and Vega-Tooltip libraries.