USPS Homepage

213 Secondary Address Unit Designators

Unit designators are printed on delivery address line.Secondary address unit designators, such as APARTMENT or SUITE, are required to be printed on the mailpiece for address locations containing secondary unit designators. The preferred location is at the end of the Delivery Address Line. The pound sign (#) should not be used as a secondary unit designator if the correct designation, such as APT or STE, is known or is shown in the ZIP+4 file.

213.1 Common Designators

The most common unit designators are:

 

APARTMENT

APT

BUILDING

BLDG

FLOOR

FL

SUITE

STE

UNIT

UNIT

ROOM

RM

DEPARTMENT

DEPT

Note: See Appendix C2 for approved designators.

213.2 Pound Sign (#)

Pound sign preceding an apartment number.If the pound sign (#) is used, there must be a space between the pound sign and the secondary number.

213.3 Alternate Location

Unit designator above the delivery address line.If all Delivery Address Line information cannot be continued in the Delivery Address Line above the city, state, and ZIP Code, place secondary address information on the line immediately above the Delivery Address Line.