The E branch (also referred to as the Huntington Avenue branch, or formerly as the Arborway Line) is a light rail line in Boston, Massachusetts, operating as part of the Massachusetts Bay Transportation Authority (MBTA) Green Line. The line runs in mixed traffic on South Huntington Avenue and Huntington Avenue between and (the last MBTA street-running tracks in revenue service), in the median of Huntington Avenue to , then into the Huntington Avenue subway. The line merges into the Boylston Street subway just west of , running to via the Tremont Street subway.