Updated 2026-10-22 · 6 min read
How to Write a US Address
A US address looks simple until a form rejects it. The order is fixed: street address, optional apartment or suite, city, two-letter state, and ZIP code. This guide explains each line, the places people get stuck, and how to format the same address for domestic and international mail.
The standard US address order
For mail inside the United States, write the recipient name first, then the street address, then the city, state, and ZIP code. The country line is not needed for domestic mail, but many web forms ask for it anyway.
The postal convention is designed to be read from the bottom up by sorting machines: ZIP, state, city, street. That is why the ZIP and state belong on the same line as the city, not on a separate line above it.
- Recipient name
- Street address, including the apartment, suite, or unit number
- City, state abbreviation, and ZIP code
- Country (international mail only)
What belongs on address line 1
Address line 1 is the primary delivery line. It contains the building number, street name, and any directional or street-type suffix. If the address has an apartment, suite, floor, or unit, that belongs on line 2, not line 1.
A street address such as “1234 SW Morrison St” is line 1. A PO box is also line 1 when it is the delivery point, for example “PO Box 4421”. Do not mix a street address and a PO box on the same line unless the postal operator specifically requires it.
What belongs on address line 2
Line 2 is the secondary unit designator. It answers “which unit inside this building?” Use it for apartment, suite, floor, room, unit, building, or department. If there is no secondary unit, leave line 2 blank; do not write “N/A” or repeat the city.
Some forms label line 2 as “Apartment, suite, etc. (optional)”. Others use line 2 for a company name or attention line. Follow the form’s label, but keep the street and unit separate so a shipping label can print cleanly.
State abbreviations and ZIP codes
Use the two-letter USPS state abbreviation, not the full state name, in the city/state/ZIP line. California is CA, New York is NY, and the District of Columbia is DC. The abbreviation is uppercase and has no period.
A standard US ZIP code is five digits. ZIP+4 adds a hyphen and four more digits, for example 97205-1234. ZIP+4 is optional for most personal mail but can be required by a bulk-mail or address-validation system. Do not invent a ZIP+4; use it only when you have the full code.
| Field | Example | Notes |
|---|---|---|
| Line 1 | 1234 SW Morrison St | Building number and street name |
| Line 2 | Apt 5B | Optional secondary unit |
| City | Portland | No state name here |
| State | OR | Two-letter USPS abbreviation |
| ZIP | 97205 | Five digits; ZIP+4 is optional |
International mail and forms
For mail from another country, add the country name in uppercase on the last line. Write “UNITED STATES” or “USA”, not a state name alone. The destination country should be the last line so the foreign postal service can route the item before USPS reads the street line.
Web forms often split the address differently. If a form has “Address line 1”, “Address line 2”, “City”, “State”, and “ZIP”, put the street on line 1, the unit on line 2, and the city/state/ZIP in their own fields. Do not paste a full address into the street field just because it fits.
Common mistakes
Most rejected addresses are not exotic. They are formatting problems: a full state name in a two-letter field, a ZIP in the city field, an apartment number on line 1, or a country name mixed into the street line. Fix the field structure before you assume the address is invalid.
- Writing “California” instead of “CA” in a two-letter state field.
- Putting the ZIP code on a separate line from the city and state.
- Combining the apartment number with the street number.
- Using a PO box and a street address on the same line.
- Adding a country name to a domestic address.
Questions
- Only when the delivery point has a secondary unit such as an apartment or suite. If there is no unit, leave it blank. Do not write “N/A” in a field that a label printer may print literally.
- In US addresses, the ZIP goes after the state abbreviation on the same line: Portland, OR 97205. In some other countries the postal code comes before the city, so do not generalize the US order to every country.
- In ordinary writing, yes. In a USPS-formatted address or a form with a two-letter state field, use the abbreviation. Mixing a full name into a two-letter field is a common validation failure.
- On the last line for international mail. For domestic US mail, the country line is optional and often omitted. If a web form requires it, use “United States”.