The visualization aggregates reported foodborne illness outbreaks by month, summing illnesses and color-coding bars by primary transmission mode. It filters out records with missing transmission data from a public national outbreak dataset. Built with React, D3 v5’s `csv` loader, and the Vega-Lite API, the bar chart uses `markBar`, `fieldQ('Illnesses').aggregate('sum')`, and `fieldN('Primary Mode')` for color encoding, with custom axis and label styling from a shared config.