Barrios de Maryland O

• Oakenshawe (8)
• Oakland Mills (4)
• Oaklee (1)
• Oakview (1)
• Old Ellicott City (1)
• Old Farm (1)
• Old Town Hyattsville (26)
• Oldtown (1)
• Oliver (10)
• Otterbein (7)
• Outer Downtown/Maugansville (31)
• Outer Robinwood/Paramnt/Fountain Head (11)
• Overlea (11)
• Owen Brown (8)