15 BUSIEST TRANSIT DISTRICTS

No. 1: MTA New York City Transit (New York City) | Total passengers in 2012: 2,544,892,400
No. 2: Washington Metro Area Transit Authority (D.C.) | Total passengers in 2012: 280,904,200
No. 3: Chicago Transit Authority (Chicago) | Total passengers in 2012: 231,154,300
No. 4: Massachusetts Bay Transportation Authority (Boston) | Total passengers in 2012: 165,028,800
No. 5: San Francisco Bay Area Rapid Transit District (San Francisco) | Total passengers in 2012: 123,219,300
No. 6: Southeastern Pennsylvania Transit Authority (Philadelphia) | Total passengers in 2012: 98,171,300
No. 7: Port Authority of New York & New Jersey (Jersey City, N.J.) | Total passengers in 2012: 70,548,400
No. 8: Metro Atlanta Rapid Transit Authority (Atlanta) | Total passengers in 2012: 70,506,800
No. 9: Los Angeles County MTA (Los Angeles) | Total passengers in 2012: 48,703,700
No. 10: Miami-Dade Transit Agency (Miami) | Total passengers in 2012: 19,242,800
No. 11: Maryland Transit Administration (Baltimore) | Total passengers in 2012: 15,399,400
No. 12: Puerto Rico Department of Transportation (San Juan) | Total passengers in 2012: 11,023,500
No. 13: Port Authority Transit Corp. (Lindenwold, N.J.) | Total passengers in 2012: 10,612,900
No. 14: Greater Cleveland Regional Transit Authority (Cleveland) | Total passengers in 2012: 6,239,900
No. 15: MTA Staten Island Railway (New York City) | Total passengers in 2012: 4,445,100

Among the busiest US transit systems, Boston's MBTA is near the top - Boston Business Journal