Notice: this is a list of the busiest U.S. bus agencies by ridership. The key here is to remember this is a list
by agency--and not a list of riderhip on every agency that runs buses in any particular city or metropolitan area. Also, for simplicity's sake, I'm combining ridership on both motor buses and trolley buses. All figures from APTA.
20 Busiest Bus Agencies in the United States
Average weekday ridership,
by agency:
01. New York (MTA) - 2,608,200
02. Los Angeles (MTA) - 1,122,800
03. Chicago (CTA) - 895,700
04. Philadelphia (SEPTA) - 547,300*
05. San Francisco (Muni) - 509,200*
06. Washington (WMATA) - 457,300
07. Seattle (Metro Transit) - 406,500*
08. Boston (MBTA) - 401,400*
09. Baltimore (MTA) - 264,800
10. Miami (M-DTA) - 239,500
11. Houston (MTA) - 232,100
12. Minneapolis (Metro Transit) - 232,000
13. Portland (TriMet) - 207,200
14. Denver (RTD) - 200,300
15. Atlanta (MARTA) - 195,500
16. Pittsburgh (Port Authority) - 175,900
17. San Diego (SDMTS) - 173,000
18. Orange County, CA (OCTA) - 154,300
19. San Antonio (VIA) - 132,400
20. Ft. Lauderdale (BCT) - 131,600
*Combined motor bus and trolley bus ridership
**New Jersey Transit did not provide APTA with daily ridership stats. My best guesstimate based on reported quarterly ridership is NJT provides 400,000 bus trips each weekday, ranking it #9 in the nation.
***Oakland's AC Transit does not provide APTA with ridership stats, but the Contra Costa Times
estimates average weekday bus ridership at 200,000, ranking AC Transit #15 in the nation.