Initially, the Sixth Avenue Line carried only local service, since there were no express tracks between 34th Street and West 4th Street. In 1967 and 1968, the Chrystie Street Connection was completed, connecting the line with former BMT lines in Brooklyn via the Manhattan Bridge and with the BMT Jamaica Line over the Williamsburg Bridge. Two new stations at 57th Street and Grand Street, as well as a pair of express tracks between 34th and West 4th Streets, were built to provide the necessary capacity for the new service to Brooklyn.