How a US Mailing Address Is Structured, Line by Line

Address basics  |  April 6, 2026  |  2 min read

A US mailing address looks simple, but every line has a job. Mail sorting machines read addresses from the bottom up, so the order and spacing of each part matters more than most people think. Here is how a standard domestic address is built.

The recipient line

The first line names the person or business receiving the mail. For businesses, you can add an attention line such as "ATTN: Accounts Payable" either above or below the company name. Keep it on its own line so it never collides with the delivery address.

The delivery address line

This is the most important line for the carrier. It contains the primary number (the house or building number), an optional directional (N, S, E, W), the street name, the street suffix (ST, AVE, RD) and an optional post-directional. Example: 1420 N MAPLE AVE.

The secondary unit

Apartments, suites, floors and units belong at the end of the delivery line when they fit: 1420 N MAPLE AVE APT 3B. If the line runs too long, USPS allows the unit to sit on the line directly above the street line, never below it.

The last line: city, state and ZIP

The final line holds the city name, the two-letter state abbreviation and the ZIP code, for example SPRINGFIELD IL 62704. A ZIP+4 code, such as 62704-1532, narrows delivery to a specific block face or building.

A complete example

• JANE MILLER
• ACME SUPPLY CO
• 1420 N MAPLE AVE STE 210
• SPRINGFIELD IL 62704-1532

Formatting tips that help machines

• Use uppercase letters where you can.
• Leave out punctuation except the hyphen in a ZIP+4 code.
• Use the standard USPS abbreviations for suffixes and units.
• Keep the address left aligned with no blank lines between parts.

When you test forms, databases or label printers, a generated address that follows this exact structure is the fastest way to confirm each field lands in the right place. Our generator produces addresses in this same order so you can paste them straight into your test cases.