US address format guide

How to Fill Out a US Address: Street, City, State, and ZIP Code

Most US address-form errors come from putting the right value in the wrong field. Here is the field mapping, followed by four address samples I generated and checked by state.

By the AddressLab Operations TeamReviewed and updated：July 29, 2026Data and editorial standards

The short answer

Street / Address Line 1: House number and street name, such as 1315 K St
City: The city or locality, such as Sacramento
State: The state, usually as a two-letter USPS abbreviation such as CA
ZIP Code: The five-digit postal code, such as 95814
Country: United States or US, when the form asks for it

Put together, the example is 1315 K St, Sacramento, CA 95814, United States.

What I tested in AddressLab

On July 29, 2026, I selected California, New York, Delaware, and Texas one at a time in the English US Address Generator. I generated one record for each state and checked whether the City, State, and ZIP Code stayed consistent with the selected state. Names, phone numbers, and temporary email addresses were outside this test.

California selected in the English AddressLab US Address Generator — I used the state selector instead of random mode so that each generated result had an expected state value.

Selected state	Generated Street	City	State	ZIP Code
California	3841 Olympic Blvd	Los Angeles	CA	90012
New York	3527 Washington Ave	Albany	NY	12207
Delaware	9555 Walnut St	Wilmington	DE	19801
Texas	165 6th St	Austin	TX	78701

All four records kept the city, state abbreviation, and ZIP Code within the selected state. For QA work, this fixed-state mode is more useful than repeatedly generating random records: a test can assert the expected state first, then check the dependent fields, saved-address display, and export.

What belongs in Street or Address Line 1?

Street normally means the primary delivery line: house number followed by street name. In the California screenshot below, that field is 1315 K St.

If the address includes an apartment, suite, room, or unit, put that detail in Address Line 2 when the form provides one. USPS-recognized secondary unit designators include APT, STE, UNIT, and RM. A form with no second line may accept the unit after the street, for example 1315 K St APT 3B.

Do not put the city or state in this field. That may look harmless in a visual preview but creates duplicate values in saved records and API payloads.

How City, State, and ZIP Code fit together

USPS calls the city, state, and ZIP Code the last line of a domestic address. In a web form, these values are usually separated:

City: enter the locality, such as Sacramento.
State: choose the state name from a list, or enter its official two-letter abbreviation in a text field.
ZIP Code: enter the five-digit code unless the form explicitly supports ZIP+4.

Store ZIP Codes as text, not numbers. A valid code such as 02108 loses its leading zero when software converts it to the number 2108. This bug often appears after CSV import or when a database column uses an integer type.

Generated California address with separate Street, City, State, ZIP Code, and Country fields — This separate California run produced Sacramento, California (CA), and 95814 as a consistent field set.

Web form format versus mailing-label format

A web form stores the example as individual values:

Address Line 11315 K St

CitySacramento

StateCA

ZIP Code95814

CountryUnited States

A domestic mailing label would commonly show the same data as:

AMELIA MARTIN
1315 K ST
SACRAMENTO CA  95814

The label version omits commas and the country because it follows a US domestic mailing convention. A checkout confirmation can still use commas for readability. The important part is preserving the correct field values, not forcing a mailing-label presentation into every interface.

Five mistakes worth testing

State entered as City: Sacramento belongs in City; California or CA belongs in State.
Invented state abbreviations: use CA, not CAL or Calif.
ZIP Code stored as a number: this removes leading zeros from codes in states such as Massachusetts.
Phone area code used as ZIP Code: the two codes serve different purposes and are not interchangeable.
A formatted sample treated as a delivery address: consistent fields do not confirm that a synthetic house number receives mail.

Where a generated address helps, and where it stops

AddressLab is useful when I need separate values for a signup form, checkout prototype, saved-address card, JSON payload, or CSV export. Each field can be copied on its own, which makes it easier to isolate a failing input instead of pasting and splitting a complete address.

AddressLab field grid with copy buttons for each generated address value — The copy control beside each value is useful when a test needs to fill one form field at a time.

The limitation matters: AddressLab uses synthetic test data. The dataset keeps City, State, and ZIP Code combinations structured, but it does not prove that a generated house number is a real residence or a deliverable destination. Do not use these samples for shipping, identity checks, account verification, or financial activity. See the data methodology and editorial standards for the documented boundary.

A quick check before submitting the form

Read the values back in this order: house number and street, city, two-letter state code, five-digit ZIP Code. Then inspect the combined preview to catch a value that landed in the wrong input.

Use the US Address Generator when you need a complete test record. If the form has strict postal validation, continue with the ZIP Code field testing checklist.