This line chart visualizes the popularity of US airlines based on passenger numbers at San Francisco Airport from 2005 to 2019. The D3 v4 implementation renders an SVG chart with smooth animated lines, using the Bulma CSS framework for page styling. The visualization compares passenger volumes across multiple airlines over time, with data structured as arrays of date-value pairs. The code includes axis rendering, styled line paths, and interactive navigation within a React-based gallery page.