Barrios de Massachusetts O

• Oak Grove (20)
• Oak Grove-Pine Banks (10)
• Oak Hill (18)
• Oak Island (14)
• Oak Square (6)
• Oakland Vale (24)
• Old Hill (2)
• Outer Fitchburg/Leominster (15)
• Outer Quincy/Milton/Randolph (9)
• Outer Route 1 South (45)
• Outlying Quincy-Milton (27)