The southbound B47 begins at the Woodhull Medical Center in Bedford–Stuyvesant, near the intersection of Marcus Garvey Boulevard and Ellery Street.

It next turns right at Avenue U where it continues until its terminus at East 54th Street, in front of the Kings Plaza Shopping Center in Mill Basin.

[7] Service on the line used to originate at the Williamsburg Bridge Trolley Terminal on the Lower East Side of Manhattan, but was cut back to Washington Plaza in Brooklyn in 1949.

The B78 replaced the southern portion of the Ralph Avenue Line, and traveled from the Sutter Avenue–Rutland Road subway station in Brownsville to the Kings Plaza Shopping Center.

The B40 and B78 routes were discontinued September 8, 2002, and the Ralph Avenue portion of the B40 merged with the B78 at that time to form the current B47.