The following is a list of all light rail systems in the United States, ranked by ridership. Also included are some of the urban streetcar/trolley systems that provide regular public transit service (operating year-round and at least five days/week), ones with data available from the American Public Transportation Association's (APTA) Ridership Reports. This list does not include statistics for metro/rapid transit systems (see: the List of United States rapid transit systems by ridership for those). Daily and annual ridership figures are based on "average weekday unlinked passenger trips" (where transfers between lines are counted as two separate passenger "boardings" or "trips"). References with supplementary (non-APTA) ridership figures are included in the System column.