Historically, transit bus ridership has been higher than transit rail ridership, but in recent years the two modes have had nearly the same ridership.
Transit rail ridership grew 64% from 1990 to 2018, although this growth was not continuous during the period.
Transit bus ridership saw an overall decline of 17% in that same time period.
Total transit ridership in 2018 was 9.9 billion passenger trips.
Annual Transit Ridership, 1990 - 2018
Sources: American Public Transportation Association, Ridership Report, Quarterly and Annual Totals by Mode, and Fourth Quarter 2018 Ridership, accessed May 22, 2019.