Columbia subject headings:
Local transit--New York (State)--New York.
New York (N.Y.)--Social conditions.
Railroads, Elevated--New York (State)--New York.
Harvard subject headings:
Local transit--New York (State)--New York
New York (N.Y.)--Social conditions
Poor--New York (State)--New York
Public health--New York (State)--New York
Railroads, Elevated--New York (State)--New York.
Sanitation--New York (State)--New York.
Street-railroads--New York (State)--New York
Princeton subject headings: