Why address format matters
An address typed wrong can mean your package arrives at the wrong house, your mail gets returned, or your online order never ships. The difference between a delivery that works and one that fails is often just the order of information or a missing apartment number. Most delivery systems — whether USPS, UPS, FedEx, or an online retailer — read addresses by looking for specific pieces in a specific order, so a comma in the wrong place or a missing suite number can break the whole thing.
The good news is that the format is the same almost everywhere in the United States. Once you know the order and what each line means, you can type any address correctly.
Key Takeaways
- A complete U.S. address has five parts in order: street number and name, apartment or suite number (if needed), city, state abbreviation, and ZIP code.
- The street address and apartment number go on the first line together, separated by a comma if the apartment number comes after the street name.
- City, state, and ZIP code go on the second line, with the state as a two-letter abbreviation and no periods.
- Spell out street types (Street, Avenue, Boulevard) in formal addresses, but many online forms accept abbreviations like St., Ave., or Blvd.
- Always double-check the ZIP code against the city and state, because a wrong ZIP code can send mail to a different city with the same name.
The five parts of a U.S. address in order
Every address has five pieces of information, and they must go in this order: street address, apartment or unit number, city, state, and ZIP code. If you put them in any other order, the mail carrier or delivery system may not understand where the package should go.
Line 1: Street number, street name, and apartment or suite number (if there is one). The street number comes first — for example, 425 Main Street or 1847 Oak Avenue. If there is an apartment, unit, or suite number, it goes after the street name, separated by a comma: 425 Main Street, Apt. 3B or 1847 Oak Avenue, Suite 200.
Line 2: City, state abbreviation, and ZIP code, in that order. The city name comes first, then a comma, then the two-letter state abbreviation (no periods), then a space, then the five-digit ZIP code. Example: Springfield, IL 62701.
How to format the street address line
The street address line is where most mistakes happen because people are unsure whether to abbreviate, where to put the apartment number, or how to write the street type.
Start with the street number — always a numeral, never spelled out. Then the street name, which can be one word or multiple words. Then the street type: Street, Avenue, Boulevard, Road, Lane, Drive, Court, Circle, or Place. In formal addresses and on official documents, spell these out completely. In online forms, many systems accept abbreviations like St., Ave., Blvd., Rd., Ln., Dr., Ct., or Cir., but spelling them out is always correct.
If the address includes an apartment, unit, suite, or floor number, put it after the street type, separated by a comma. Write it as Apt. 3, Unit 5, Suite 200, or Floor 12 — whichever matches the building. Some buildings use letters instead of numbers (Apt. 3B, Apt. 3C), and some use just a number. Use whatever the building uses. If you do not know the apartment number format, check the lease, a utility bill, or ask the building directly.
Examples of correct street address lines:
- 425 Main Street
- 1847 Oak Avenue, Apt. 5
- 3200 Commerce Boulevard, Suite 150
- 742 Elm Road, Unit B
How to format the city, state, and ZIP code line
The second line holds the city, state, and ZIP code. The city name comes first, spelled exactly as it appears on official documents — for example, New York, not New york or new york. Then a comma, then the two-letter state abbreviation with no periods (IL for Illinois, CA for California, NY for New York), then a space, then the five-digit ZIP code.
The state abbreviation must be two letters. Do not spell out the state name, and do not use periods. Correct: Springfield, IL 62701. Incorrect: Springfield, Illinois 62701 or Springfield, Ill. 62701.
The ZIP code is always five digits. If your ZIP code has fewer than five digits, add zeros to the front — for example, 02101 for Boston, not 2101. If you have a ZIP+4 code (the nine-digit version), you can include it, but the five-digit version is sufficient for mail delivery. Format it as 62701-1234 if you use the full nine digits.
Examples of correct city, state, and ZIP code lines:
- Springfield, IL 62701
- Los Angeles, CA 90001
- New York, NY 10001
- Portland, OR 97201
Common mistakes to avoid
The most common mistake is putting the apartment number on a separate line or in the wrong place. The apartment number must go on the same line as the street address, after the street name and separated by a comma. If you put it on a second line by itself, the mail carrier may not see it, and the package could go to the building's main address instead of your unit.
Another frequent error is spelling out the state name instead of using the two-letter abbreviation. Addresses must use abbreviations like CA, TX, FL, or NY. Spelling out "California" or "Texas" can cause the address to be rejected by automated sorting systems.
Misspelling the city name or using a nickname instead of the official name is also common. For example, some people write "San Fran" instead of "San Francisco," or "LA" instead of "Los Angeles." Always use the full, official city name as it appears on government documents and maps.
Finally, double-check the ZIP code. Many cities share the same name across different states — there is a Springfield in Illinois, Missouri, Massachusetts, and several other states. If you use the wrong ZIP code, your mail could go to the wrong Springfield entirely. Verify the ZIP code against the city and state using USPS.com or a similar resource.
How to verify an address before sending
Before you submit an address for a delivery or important document, take 30 seconds to verify it. The USPS website (USPS.com) has a free address lookup tool. Type in the street address, city, and state, and it will show you the correct format and ZIP code. This catches typos and confirms that the address exists.
If you are typing an address for an online order, most retailers will show you the formatted address before you confirm payment. Read it carefully — does the street name match what you typed, is the apartment number there, and is the city spelled correctly? If anything looks wrong, go back and fix it.
For addresses you use often, save them correctly the first time. Once an address is stored in your contacts, email, or online account, you can reuse it without retyping it and risking new mistakes.
Frequently Asked Questions
Do I need to capitalize every word in an address?
Capitalize the first letter of each word in the street name, city name, and street type — for example, Main Street, Los Angeles, or Oak Avenue. You do not need to capitalize every letter. The state abbreviation is always two capital letters (CA, TX, NY), and the ZIP code is always numerals.
What if the address has a PO Box instead of a street address?
A PO Box address follows the same format: PO Box number on the first line, then city, state, and ZIP code on the second line. Example: PO Box 1234, Springfield, IL 62701. Do not include a street address if you are using a PO Box.
Should I use periods in abbreviations like "St." or "Ave."?
Periods are optional in modern address formatting. Both "St." and "St" are accepted by postal systems and online forms. For consistency, choose one style and stick with it. Spelling out the full word (Street, Avenue) is always correct and avoids any ambiguity.
What if I do not know the apartment number?
Contact the person or business at that address and ask for the apartment number. If you are sending a package to someone, ask them directly. If you cannot reach them, you can try sending it to the street address without the apartment number, but it may be delivered to the building's main office or returned. It is better to wait and get the correct apartment number.
Can I use abbreviations for street types like "Rd" or "Ln"?
Yes, abbreviations are widely accepted in online forms and by delivery services. Common abbreviations include St. (Street), Ave. (Avenue), Blvd. (Boulevard), Rd. (Road), Ln. (Lane), Dr. (Drive), and Ct. (Court). Spelling them out completely is also correct and sometimes preferred for formal documents.