US address format explained: streets, state abbreviations & ZIP codes

2025-01-25 · US Address Generator

The standard two-line US address

A US address runs specific to general in exactly two lines, plus optional recipient and unit lines. The house number precedes the street; the second line carries city, state abbreviation and ZIP:

Marilyn Monroe          ← recipient
1234 Oak Street         ← house number + street
Apt 5                   ← unit (optional)
Los Angeles, CA 90001   ← city, two-letter state, ZIP

Line two keeps that exact order, with a comma between city and state and a two-letter uppercase abbreviation. Los Angeles, California, 90001 passes many systems, but any serious address normalizer will compress it to the shape above — write it correctly to begin with.

Official USPS abbreviations (Publication 28)

USPS address standards live in Publication 28, which includes an official suffix table: Street → ST, Avenue → AVE, Boulevard → BLVD, Drive → DR, Road → RD, Lane → LN, Court → CT, Place → PL, Terrace → TER, Parkway → PKWY, Circle → CIR, Highway → HWY.

Directionals abbreviate too: North → N, South → S, East → E, West → W, Northeast → NE, Southwest → SW. "1234 North Oak Street" standardizes to 1234 N OAK ST.

ZIP and ZIP+4

A ZIP is always five digits and its prefix is bound to a state: 100xx Manhattan, 606xx Chicago, 900xx Los Angeles, 981xx Seattle, 331xx Miami. Mismatch the prefix and validation fails.

ZIP+4 appends a hyphen and four digits, as in 60601-1234, narrowing to a block or building. Everyday forms want five digits; USPS adds the extra four during standardization.

Five common errors

1. State written out or lowercased: ca and California both break dropdowns; CA is correct.
2. Reversed house and street: Oak Street 1234 is the European order; the US puts the number first.
3. Wrong ZIP length: four digits, six digits or letters are all invalid.
4. Neighbourhood instead of postal city: the city field takes the postal city, not a subdivision name.
5. Inverted country line: on international mail USA goes last, uppercase — many templates put it first.

APO / FPO and territory addresses

Military mail uses APO or FPO with AE, AP or AA in the state slot followed by a ZIP, and the city field carries the APO/FPO number. Territories such as Puerto Rico use their own two-letter code (PR) and ZIP ranges. A form hard-coded to 50 states cannot accept any of these.

What to check in a form

• Is the state field a dropdown or free text? Does a dropdown include DC and the five territories?
• Does the ZIP input accept digits only, cap at five, and reset when the state changes?
• After choosing the US, is the country pinned to the last line in international display?
• Do optional unit and address-line-2 fields stay quiet when empty?
• Does the phone field accept +1, enforce ten digits and display 3-3-4?

Try it with data

The US address generator filters by state and city with prefixes bound to each state, covering all five checks. The state list has abbreviation mappings for all 50 states plus DC, and the ZIP database reverses a ZIP to its city.