US address format for forms, QA, and international users
A practical guide to street lines, city, state abbreviation, ZIP code, county, phone format, and common validation mistakes.
What a standard US address looks like
A common US mailing address includes a recipient name, street address, optional apartment or unit line, city, two-letter state abbreviation, and ZIP code. Example: John Smith, 4204 Fidelity St, Houston, TX 77095.
For apartments, offices, or suites, a second line often uses Apt, Unit, Ste, or Suite. USPS Publication 28 treats these as secondary unit designators. Many international users omit that line, which can make an address look complete while still failing delivery or form validation.
US address fields explained
| Field | Example | What to check |
|---|---|---|
| Street line 1 | 4204 Fidelity St | House number, street name, and street type look plausible |
| Street line 2 | Apt 5B / Suite 200 | Optional field supports apartment or suite formats |
| City | Houston | City belongs to the selected state |
| State | TX | Uses the USPS two-letter abbreviation when required |
| ZIP | 77095 | Matches the city and state fixture |
| Phone | +1 713 ... | Area code fits the region |
Street lines: where low-quality data hides
Many random address generators combine house numbers, street names, and street types without keeping city, state, and ZIP aligned. The result may look like an address but adds little testing value.
Common street types include St, Ave, Blvd, Rd, Dr, Ln, and Ct. Forms that accept only full words, or only abbreviations, can both create real-user friction.
City, state, and ZIP must be validated together
US ZIP codes are five digits, with an optional ZIP+4 extension. For most sign-up forms, billing addresses, and software tests, five digits are enough.
The critical part is consistency. Houston should pair with TX and a Houston-area ZIP; Los Angeles should pair with CA; New York City should pair with NY. Checking only that a ZIP has five digits does not prove the address is valid.
USPS Publication 28 recommends two spaces between the state abbreviation and ZIP+4 when possible. Many web forms ignore that spacing rule, but QA teams should still test both five-digit ZIP and ZIP+4 acceptance paths.
Common form and QA bugs
- Validating ZIP length but not city-state consistency.
- Translating the state name into another language without storing the two-letter code.
- Requiring ZIP+4 when ordinary five-digit ZIP is sufficient.
- Rejecting Apt, Unit, or Suite even though many real addresses need them.
- Accepting only local US phone formats and rejecting +1 international formats.
- Treating county as required even though many users do not know their county.
Recommended test set
Prepare at least three US address fixtures: a standard residential address, an address with Apt or Suite, and a cross-state comparison address. Adding California, New York, Texas, Delaware, and Oregon covers most common form-validation issues.