There are two different standards for counting ridership.  There is unlinked trips (boardings) and linked trips (revenue riders).  All Canadian systems count linked trips while American systems count unlinked trips, and 430 million figure for Toronto is linked trips, and not comparable to any ridership figure for any American transit system. According to the APTA website, the Toronto Transit Commission had over 700 million boardings in 2005, while Chicago only had over 400 million boardings.  So what is stated on this site that Chicago Transit Authority is a larger system than the TTC is completely false and should be changed.