US Address Format Details: Apt Placement, Street Suffixes, 10 Traps
2026-09-15 · US Address Generator
Most US address errors are not about spelling — they are about format details: does Apt go in Line 1 or Line 2? Can I write St or does it have to be Street? This guide covers the details that cause validation failures.
1. Line 1 vs Line 2
- Address Line 1: house number + street only, e.g. 1234 Oak Street.
- Address Line 2: apartment, unit, suite, floor. E.g., Apt 5.
The most common error is putting the apartment in Line 1.
2. Street suffix abbreviations
| Abbr | Full |
|---|---|
| St | Street |
| Ave | Avenue |
| Blvd | Boulevard |
| Rd | Road |
| Dr | Drive |
| Ln | Lane |
| Pl | Place |
| Way | Way |
Directional prefixes also matter: N/S/E/W and combos like NW or E: “ 456 N 9th St”. Direction can split two distinct addresses.
3. Apt / Unit / Suite
They always go in Line 2. Write them as word + number: Apt 5, Unit 3B, Suite 200 / Ste 200.
4. City, State, ZIP format
One line: Los Angeles, CA 90001 — full city name, comma, two-letter uppercase state abbreviation, space, 5-digit ZIP. The state must usually match the dropdown.
5. Ten traps that fail forms
- Apt in Line 1 instead of 2.
- Directional N/S/E/W omitted from an address that needs it.
- Full state name instead of the abbreviation.
- ZIP that does not match the state or city.
- Reversing the Chinese (big-to-small) vs US (small-to-big) address order.
- Mixing suffixes for the street (St vs. Street) inconsistently.
- Since building name instead of an apartment number.
- Unit/Suite letter casing inconsistent (Suite 3 vs suite 3).
- Filling ZIP+4 but missing the base 5-digit ZIP.
- Answering an address with PO Box into a delivery line that expects a physical street.
Generate well-formatted sample addresses with the US address generator, check structure with the address formatter, or reread the US address format guide.