How an address is written in the United States

An address in the United States is written in this order: house number and street name, then town or city, state and ZIP code on one line, with the town or city and the state in capitals. The strongest check here is a building-level one: the US Department of Transportation's National Address Database lists 84,692,955 addresses in the United States (version 6 September 2026), though not every address there.

The order the lines go in

The parts are named rather than filled in: Spaw does not know an address in the United States and will not invent one. This block is produced by the same function that rewrites a real address, so the line order, the capitals the United States asks for and any text its operator prints on every envelope are the checker's own behaviour rather than a second description of it.

Organisation
12 Street name
Flat or unit
TOWN OR CITY, STATE ZIP code

No recipient line: nothing in the response is about a person, so the name the envelope carries is not part of what is checked.

field	called here	required	capitals
organization	Organisation	optional	—
addressLine1	Street name	required	—
addressLine2	Flat or unit	optional	—
locality	Town or city	required	yes
administrativeArea	State	required	yes
postalCode	ZIP code	required	—

No house-number rule is carried for the United States, so the international default is used: the house number comes before the street name. The ZIP code is written after the town.

Can Spaw tell whether an address in the United States exists?

Partly. The US Department of Transportation's National Address Database lists 84,692,955 addresses in the United States (version 6 September 2026), but not every address there: a partial address register confirms what it holds and denies nothing. An address that is listed answers exists: true; one that is not answers null — not evaluated, never no.

The US Census Bureau's TIGER/Line address ranges adds streets and the range of house numbers on each side of them, never buildings: where the register above has no match, a street can still be confirmed there, and a building cannot.

A postcode directory answers a different question. The ZIP code is settled separately by GeoNames' postal code list, which is recorded as complete: one it does not hold answers postcode_not_found.

register	covers	lists	coverage	version
The US Department of Transportation's National Address Database us-national-address-database	United States	84,692,955 addresses	partial	2026-09-06
The US Census Bureau's TIGER/Line address ranges us-tiger-address-ranges	United States	53,135,059 streets	partial	2025-09-22

Further reading: How to read an address-existence answer, How an open register locates a building and Number ranges: what the US range match can and cannot say.

Check an address in the United States

The same lookup the API runs, with United States already selected.

Live demo

POST /demo/address · no key needed

try:

Response

Look up any address to see the full API response, straight from the live service. The country decides which format it is read against.

Every field in the response Get your API key

The ZIP code

ZIP codes in the United States are checked against the pattern below rather than a description of it, because the shape is too particular to summarise without losing a case.

pattern (\d{5})(?:[ \-](\d{4}))?

A postcode list from a multi-country source is installed for the United States, so a ZIP code here is not only checked for shape but looked up: 41,488 ZIP codes from GeoNames' postal code list, version 2026-10-03. It lists current codes only, so a retired code is not told apart from one it does not hold.

What the United States calls an address that is not a front door

A PO box, a private mailbox and the other kinds of delivery point below are told apart by the words written on the address, never by a list of whose box is whose. The rows marked as the operator's own words are taken from the addressing guide of the postal operator in the United States; the others are international spellings, not the operator's own. All of them are what the checker reads, and because an entry is carried for the United States, an address here with none of them answers street.

address_type	written as
private_mailbox Private mailbox at a mail-receiving agency	PMBinternational spellings the checker also reads
po_box Post-office box	PO BOX, P O BOX, POST OFFICE BOX, POB; CALLER, FIRM CALLER, BIN, LOCKBOX, DRAWER (only at the start of a line, with a number)the operator's own words
general_delivery Held at the counter for collection	GENERAL DELIVERYinternational spellings the checker also reads
military Military and diplomatic mail	APO, FPO, DPO; PSC, CMR (only at the start of a line, with a number)the operator's own words
rural_route Rural route	RR, HC, RFD, RURAL ROUTE, HIGHWAY CONTRACT, STAR ROUTE (only at the start of a line, with a number)the operator's own words

The anchored spellings are the conservative half of this: those words are ordinary language elsewhere in an address, so they only count when they open the line and carry a number after them.

The state codes

62 codes, which is what lets a written address be split at all — and the state written out in full is folded onto its code, so the two spellings are read as the same place.

AL Alabama
AK Alaska
AS American Samoa
AZ Arizona
AR Arkansas
AA Armed Forces (AA)
AE Armed Forces (AE)
AP Armed Forces (AP)
CA California
CO Colorado
CT Connecticut
DE Delaware
DC District of Columbia
FL Florida
GA Georgia
GU Guam
HI Hawaii
ID Idaho
IL Illinois
IN Indiana
IA Iowa
KS Kansas
KY Kentucky
LA Louisiana
ME Maine
MH Marshall Islands
MD Maryland
MA Massachusetts
MI Michigan
FM Micronesia
MN Minnesota
MS Mississippi
MO Missouri
MT Montana
NE Nebraska
NV Nevada
NH New Hampshire
NJ New Jersey
NM New Mexico
NY New York
NC North Carolina
ND North Dakota
MP Northern Mariana Islands
OH Ohio
OK Oklahoma
OR Oregon
PW Palau
PA Pennsylvania
PR Puerto Rico
RI Rhode Island
SC South Carolina
SD South Dakota
TN Tennessee
TX Texas
UT Utah
VT Vermont
VI Virgin Islands
VA Virginia
WA Washington
WV West Virginia
WI Wisconsin
WY Wyoming

What can be checked for an address in the United States

Read from the datasets this server holds right now, not written into the page. For most countries the answer is the written form and the postcode shape and nothing beyond them — in particular not the row people assume is always there.

check	for US	what the answer means
Written form	yes	The address is split into the country's own parts and rewritten in the order above. A missing required part is named in one typed reason rather than a general failure.
ZIP code pattern	yes	Checked against the pattern the table carries for the United States. A value that does not match answers invalid_postal_code.
ZIP code exists	yes	41,488 ZIP codes from GeoNames' postal code list. It lists current codes only, so a retired code is not told apart from one it does not hold.
Kind of delivery point	yes	The operator's own box words are carried for the United States, so an address with no marker answers street rather than unknown.
Street exists	yes	The address register carries every street its buildings stand on, so match_level answers street when the street is known and the building is not.
Building exists	yes	84,692,955 addresses in the United States from the US Department of Transportation's National Address Database. It does not list every address in the United States, so a match answers exists: true and a miss still answers null.
Companies at the address	yes	An open company register is installed for this country, so the number of companies giving the address as their registered office is counted, and a published threshold marks it as a mail drop.
Known mailbox branch	yes	Mailbox operators' own published branch lists cover this country, and the answer names the operator that matched.
Post actually arrives	no	Not from this page, and not from open data in any country: whether post is delivered, and the vacant, residential and agency flags that go with it, are the postal service's own licensed product. Those fields answer deliverability_checked: false rather than a guess.

Null means not evaluated, never no.

Other countries

Sources

Google's Address Data Service · address-formats 2026-09-05© Google LLC, CC BY 4.0 (Google Address Data Service); initial import via commerceguys/addressing (MIT)
The postal operators' addressing guides · address-rules 2026-09-17
The US Department of Transportation's National Address Database · us-national-address-database 2026-09-06U.S. Department of Transportation, National Address Database (public domain; not a mailing list)
The US Census Bureau's TIGER/Line address ranges · us-tiger-address-ranges 2025-09-22U.S. Census Bureau TIGER/Line (public domain)
GeoNames' postal code list · geonames-postal-codes 2026-10-03Postal codes, places and centroids from GeoNames (geonames.org), CC BY 4.0.
The open company registers · company-registers 2026-10-01Colorado Secretary of State business entity data (public domain); New York Department of State active corporations (public domain); Oregon Secretary of State active business registry (public domain); Connecticut Secretary of the State business registry, via the Connecticut Open Data portal (data.ct.gov); Hawaii Department of Commerce and Consumer Affairs business registrations, via the Honolulu open data portal (data.honolulu.gov)
Mailbox operators' published branch lists · mail-drop-locations 2026-10-03

Data synced on 2026-10-03: the newest version among the datasets listed above.

Wrong result, or is it about you? If this tool said something you think is wrong, tell us and a person reads it. If Spaw is holding data about you and you never signed up here — a customer may have had your address verified, or reported that a message to it bounced — erase it yourself, confirmed by mail to that address and with no account needed.

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