This example visualizes state population growth over time for California, Michigan, and Texas using three colored line charts plotted from 1910 to 2010. Each line is labeled with the state’s name and current population. Built with D3 v4 and React, it uses `d3.scaleLinear` for axes, `d3.line` for path generation, and `d3.json` to load data from a static JSON file. A tooltip, triggered by mouse movement over a transparent overlay rectangle, displays the population ranking for the nearest decade and draws a vertical reference line.