The following is a list of all heavy rail rapid transit systems in the United States . It does not include statistics for bus or light rail systems (see: List of United States light rail systems by ridership for the latter). All ridership figures represent "unlinked" passenger trips (i.e. line transfers on multi-line systems register as separate trips). The data are provided by the American Public Transportation Association 's Ridership Reports.

System Transit agency City/Area served Annual ridership
(2015)
Avg. weekday ridership
(Q4 2015)
System
length
Rider. per mile Opened Stations Lines
1. New York City Subway New York City Transit Authority New York City 2,772,647,200 9,144,700 233 miles (375 km) 39,248 1904 469 24
2. Washington Metro Washington Metropolitan Area Transit Authority Washington, D.C. 261,435,200 836,800 117 miles (188 km) 7,152 1976 91 6
3. Chicago 'L' Chicago Transit Authority Chicago 241,670,000 772,900 102.8 miles (165.4 km) 7,518 1892 146 8
4. MBTA Subway
("The T")

( Blue , Orange , and Red Lines)
Massachusetts Bay Transportation Authority Boston 173,850,200 569,200 38 miles (61 km) 14,979 1901 53 4
5. Bay Area Rapid Transit (BART) Bay Area Rapid Transit District San Francisco Bay Area 135,044,500 452,600 104 miles (167 km) 4,352 1972 44 5
6. SEPTA
( Broad Street , Market–Frankford , and Norristown High Speed Lines)
Southeastern Pennsylvania Transportation Authority Philadelphia 100,093,800 343,800 36.7 miles (59.1 km) 9,368 1907 75 3
7. Port Authority Trans-Hudson (PATH) Port Authority of New York and New Jersey Manhattan ; Jersey City , and Newark 76,388,200 261,900 13.8 miles (22.2 km) 18,978 1908 13 4
8. MARTA rail system Metropolitan Atlanta Rapid Transit Authority Atlanta 72,030,500 231,700 47.6 miles (76.6 km) 4,868 1979 38 4
9. Metro Rail
( Purple and Red Lines)
Los Angeles County Metropolitan Transportation Authority Los Angeles 46,491,600 144,800 17.4 miles (28.0 km) 8,322 1993 16 2
10. Metrorail Miami-Dade Transit Miami 21,923,000 75,300 24.4 miles (39.3 km) 3,086 1984 23 2
11. Baltimore Metro Subway Maryland Transit Administration Baltimore 12,948,400 42,700 15.5 miles (24.9 km) 2,755 1983 14 1
12. PATCO Speedline Port Authority Transit Corporation Philadelphia , southern New Jersey 10,169,500 36,100 14.2 miles (22.9 km) 2,542 1936 13 1
13. Staten Island Railway Staten Island Railway Staten Island ( New York City ) 8,559,400 32,900 14 miles (23 km) 2,350 1860 22 1
14. Tren Urbano Autoridad de Transporte Integrado San Juan 8,538,200 32,800 10.7 miles (17.2 km) 3,065 2004 16 1
15. RTA Rapid Transit
( Red Line )
Greater Cleveland Regional Transit Authority Cleveland 6,437,600 17,637 19 miles (31 km) 928 1955 18 1