Five Andover place-name ZIPs, one county
The Town of Andover sits in Essex County in northeastern Massachusetts. DialWick's city ZIP table for the exact place string Andover in MA comes from GeoNames' US postal-code export (CC BY 4.0), retrieved 2026-08-03, not from a live scrape of USPS's web lookup form.
For that place string, the export yields five rows: 01810, 01812, 01899, 05501, and 05544. All five say Essex County. There is no GeoNames county split of the kind you see on multi-county city pages elsewhere in DialWick.
North Andover is a separate municipality. GeoNames lists 01845 with the place name North Andover, also in Essex County. Do not treat 01845 as an Andover street ZIP just because the two towns share a border and a name fragment.
| ZIP | Place (GeoNames) | County | Typical use note |
|---|---|---|---|
| 01810 | Andover | Essex | Primary street-delivery code for the Town of Andover |
| 01812 | Andover | Essex | Additional Andover place-name row; confirm on the mail piece before use |
| 01899 | Andover | Essex | Additional Andover place-name row; often PO Box / unique-style in directories |
| 05501 | Andover | Essex | Historically linked to IRS Andover Service Center mail; not a neighborhood street ZIP |
| 05544 | Andover | Essex | Companion unique-style Andover row; use only when the recipient prints it |
Commercial city pages sometimes fold North Andover or nearby Lawrence codes into an Andover map. This guide stays on the five primary Andover place-name rows plus the explicit North Andover note above.
Andover's municipal boundary and the postal place-name string are not identical concepts. The Town of Andover publishes its own About Andover overview for residents and visitors; that page situates the town in Essex County without publishing a full ZIP inventory. DialWick therefore does not treat the town site as a ZIP authority. The five-row GeoNames extract above is the inventory this guide uses for place-name Andover in Massachusetts.
When commercial ZIP aggregators show a colored polygon labeled Andover, they often blend delivery routes, PO Box ranges, and unique recipient codes into one blob. That blending is convenient for marketing maps and dangerous for form autofill. If a checkout form suggests 05501 because a database row says Andover, reject the suggestion unless the recipient's own stationery already shows 05501.
Essex County also hosts Lawrence, Methuen, North Andover, and Haverhill place-name ZIPs in the same GeoNames pull. Those rows are out of scope for this page except as neighbors you might confuse with Andover. Lawrence's dense 01840-range codes and North Andover's 01845 are the two most common mix-ups in shipping tickets DialWick readers report when they paste a nearby landmark instead of the house number's mail.
Street mail vs unique-style codes
If you are filling a shipping form for a house or apartment in the Town of Andover, 01810 is the code public directories treat as ordinary street delivery. Copy the five digits from recent mail to that address rather than guessing from a landmark.
05501 and 05544 appear in the same GeoNames place list because the postal export attaches the Andover place name to those rows. They are not interchangeable neighborhood ZIPs. Large single recipients (historically including federal tax-processing mail in Andover) explain why unique-style codes sit beside the town name in directories.
01812 and 01899 also share the Andover place label. Treat them like other non-primary rows DialWick shows for college towns and federal campuses: only use them when the recipient's letterhead or online checkout already prints that ZIP.
Population and alias columns on commercial sites refresh on their own schedule. DialWick's county column stays pinned to the 2026-08-03 GeoNames extract. If a commercial page disagrees on county, prefer GeoNames here and re-check USPS for delivery type.
For tax, banking, or shipping forms, the ZIP on recent mail beats a color-coded map. Marketing names for neighborhoods are not postal authorities.
IRS unique ZIP conventions are documented in IRS Internal Revenue Manual material on campus and mail-stop addressing (IRM Part 1, Submitting Documents / campus routing chapters that reference Andover-linked unique codes). Those codes exist so bulk tax mail can bypass ordinary carrier-route sorts. They are not a second street ZIP for Shawsheen or West Andover neighborhoods.
A practical rule DialWick reuses across college and federal-campus city pages: if the five digits never appear on pizza delivery menus, school directories, or utility bills for ordinary houses, treat the code as unique-style until the recipient proves otherwise. 05501 and 05544 fail that street-use smell test in public directories even though GeoNames still tags the place name Andover.
01812 and 01899 need the same skepticism. Directories sometimes list them beside PO Box or organizational mail. Copy them only from letterhead, a remittance slip, or an official contact block. Do not invent a Plus-4 to make a short ZIP look more complete; Plus-4 segments are optional and wrong Plus-4 data can delay automated sorts.
Area codes 978 and 351 are separate from the ZIP list
ZIP polygons and telephone plan areas are not the same map. DialWick's numbering extract (public NANP area-code list, retrieved 2026-08-03) puts 978 across northeastern Massachusetts, with 351 added as an overlay on that same plan area starting 2 May 2001.
A ZIP change does not move your area code, and an area-code overlay does not rewrite postal routes. Andover street addresses can show either 978 or 351 depending on when the number was issued; that choice is independent of whether the label reads 01810.
For the ZIP-versus-NPA distinction in general, see ZIP code vs area code. For other city ZIP tables built the same way, see Ames Iowa ZIP code and Amherst MA ZIP code.
Neighboring Essex place pages on DialWick draw from the same GeoNames postal export. If you need the wider contrast between U.S. ZIP labels and other countries' postal systems, open postal code vs ZIP code.
Overlay 351 did not retire 978. New numbers can draw from either code inside the shared plan area, which is why two offices on the same Andover street can show different NPAs on their business cards. That split is a numbering inventory fact, not evidence that the town has two ZIP systems.
Emergency and municipal services still key off street address and town name. Giving a dispatcher 05501 because a web form auto-filled it is worse than giving 01810 from the mailbox. Keep postal and telephone identifiers on separate mental shelves whenever you fill government, school, or medical forms for Andover residents.
Address-check workflow for Andover mail
Use this pass/fail checklist before you submit a shipping label, bank KYC form, or school registration that asks for an Andover, MA ZIP.
| Step | Action | Pass | Fail |
|---|---|---|---|
| 1 | Read the five digits on the latest envelope to that street address | Digits match what you will type | You are guessing from a map pin |
| 2 | Confirm city line is Andover, not North Andover | City and ZIP pair match the mail piece | 01845 paired with Andover (or 01810 with North Andover) |
| 3 | If the form offers 05501 or 05544, open the recipient letterhead | Letterhead prints that unique code | Autofill alone suggested the unique code |
| 4 | Ignore phone NPA when choosing ZIP | ZIP chosen without looking at 978/351 | You changed ZIP because the phone showed 351 |
| 5 | Re-check county only if the form demands it | Essex for all Andover-tagged rows here | County taken from a neighboring city page |
School and youth-sports registrations sometimes store an old ZIP after a family moves across the Shawsheen River into North Andover or Lawrence. The checklist above still applies: the current mailbox wins, not the coach's spreadsheet from last season.
Businesses that receive both street parcels and IRS remittance mail may legitimately publish two different five-digit codes on two different contact blocks. That is not permission to mix them on one label. Match the code to the mail stream (parcel vs remittance) the sender intends.
If USPS's own lookup tool and GeoNames disagree on delivery type for a non-primary row, prefer USPS for the live shipment and keep GeoNames as DialWick's county/place snapshot dated 2026-08-03. Do not silently overwrite DialWick's county column from a commercial page that omits retrieval dates.
Neighbor confusion matrix
The table below is a negative dictionary: codes people paste into Andover forms by mistake, and why they fail.
| Code or place | Actual place (typical) | Why it shows up | Use for Andover street? |
|---|---|---|---|
| 01845 | North Andover | Shared name fragment; shared Essex County | No |
| 01840 / 01841 / 01843 | Lawrence area | Adjacent city; warehouse autofill | No |
| 05501 / 05544 | Andover-tagged unique rows | GeoNames place list; IRS campus history | Only if letterhead says so |
| 01876 | Tewksbury (often) | South/west neighbor on driving directions | No |
| 01845 Plus-4 guesses | North Andover segments | Form forces Plus-4 | No; leave Plus-4 blank if optional |
DialWick's sister pages for other Massachusetts place-name tables follow the same GeoNames retrieval date. Cross-linking them does not merge their ZIP lists. Andover's five rows stay Andover's five rows even when a user arrives from an Amherst or Ames guide.
If you maintain an address book for multiple Essex County towns, store city name and ZIP as a locked pair. Sorting only on ZIP will hide the North Andover versus Andover distinction that trip tickets and tax forms still care about.