The above visualization breaks down all weekday rides on BART by their starting station. Clicking on an individual station will zoom in, showing the distribution of destination stations for that starting station.
BART provides monthly ridership data for all stations pairs - i.e. the average number of people who rode from station A to station B. They publish these datasets on their website in
.xlsx format. Those files are combined into one flat CSV in a separate repo, which is where the data used in this visualization came from.