The United States has several major cities. Some of them have [[UsefulNotes/WorldSubways subways]]. Here are the biggest ones.
* UsefulNotes/TheT (Boston)
* UsefulNotes/BayAreaRapidTransit[[/index]] (San Francisco Bay Area) and UsefulNotes/MuniMetro[[index]] (SanFrancisco itself)
* UsefulNotes/PortAuthorityTransHudson (New York and New Jersey)
* UsefulNotes/PhiladelphiaSubways (SEPTA and PATCO)
* UsefulNotes/MARTASubway (Atlanta)