Prosečne GPS koordinate za poštanski broj 01821: 42.552, -71.252
Spisak gradova:
>> Billerica 01821, Massachusetts, Middlesex, GPS koordinate: 42.5519,-71.2518
Spisak gradova:
>> Billerica 01821, Massachusetts, Middlesex, GPS koordinate: 42.5519,-71.2518