List of United States rapid transit systems by ridership
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. All ridership figures represent "unlinked" passenger trips. The data are provided by the American Public Transportation Association's Ridership Reports.
| System | Transit agency | City/Area served | Annual ridership | Avg. weekday ridership | System length | Rider. per mile | Opened | Stations | Lines | |
| 1. | New York City Subway | New York City Transit Authority | New York City | 2,274,960,100 | 9,117,400 | 37,214 | 1904 | 27 | ||
| 2. | Washington Metro | Washington Metropolitan Area Transit Authority | Washington, D.C. | 237,701,100 | 816,700 | 6,980 | 1976 | 91 | 6 | |
| 3. | Chicago "L" | Chicago Transit Authority | Chicago | 218,467,000 | 695,300 | 6,764 | 1892 | 146 | 8 | |
| 4. | MBTA subway | Massachusetts Bay Transportation Authority | Boston | 152,339,700 | 475,300 | 12,508 | 1901 | 53 | 3 | |
| 5. | Bay Area Rapid Transit | Bay Area Rapid Transit District | San Francisco Bay Area | 123,510,000 | 421,100 | 3,760 | 1972 | 48 | 7 | |
| 6. | PATH | Port Authority of New York and New Jersey | Manhattan; Hudson County, and Newark | 90,276,600 | 306,700 | 22,225 | 1908 | 13 | 4 | |
| 7. | SEPTA | Southeastern Pennsylvania Transportation Authority | Philadelphia | 90,240,800 | 329,200 | 8,970 | 1907 | 75 | 3 | |
| 8. | MARTA rail | Metropolitan Atlanta Rapid Transit Authority | Atlanta | 63,998,500 | 175,338 | 3,684 | 1979 | 38 | 4 | |
| 9. | Metro Rail | Los Angeles County Metropolitan Transportation Authority | Los Angeles | 41,775,100 | 130,900 | 7,523 | 1993 | 16 | 2 | |
| 10. | Metrorail | Miami-Dade Transit | Miami | 18,073,100 | 62,600 | 2,566 | 1984 | 23 | 2 | |
| 11. | PATCO Speedline | Port Authority Transit Corporation | Philadelphia, southern New Jersey | 11,107,500 | 38,400 | 2,704 | 1936 | 13 | 1 | |
| 12. | Staten Island Railway | Staten Island Rapid Transit Operating Authority | Staten Island | 7,741,000 | 28,500 | 2,036 | 1860 | 22 | 1 | |
| 13. | Baltimore Metro SubwayLink | Maryland Transit Administration | Baltimore | 7,325,500 | 36,600 | 2,361 | 1983 | 14 | 1 | |
| 14. | RTA Rapid Transit | Greater Cleveland Regional Transit Authority | Cleveland | 5,958,000 | 15,900 | 837 | 1955 | 18 | 1 | |
| 15. | Tren Urbano | Autoridad de Transporte Integrado | San Juan | 5,233,900 | 20,300 | 1,897 | 2004 | 16 | 1 |