Click on a station point to mark it as visited - A ✅ will appear.
Clicking on a visited station will unmark it as visited - the checkmark will be removed.
Click the Show/refresh stats button underneath the map to generate your stats based on what you've marked on the map.
This website is not optimized for mobile - I recommend visiting on a desktop device to make clicking stations easier.
Marking a station that serves multiple lines will count that station towards your overall unique station count, but will count that station on each individual line it serves.
For example, marking Howard as visited will count it as visiting one of the unique overall 146 CTA train stations. In the individual line stats, it will count towards visiting a Red, Yellow, and Purple station.