USPS Street Suffix and Unit Abbreviations You Should Know

Address basics  |  April 3, 2026  |  2 min read

The US Postal Service publishes a standard list of street suffix and secondary unit abbreviations in Publication 28. Using them keeps addresses short, consistent and easy for sorting equipment to read. If you store addresses in a database, normalizing to these forms also makes duplicate detection much easier.

Common street suffixes

Secondary unit designators

Directionals

Directions are abbreviated to one or two letters: N, S, E, W, NE, NW, SE and SW. A pre-directional sits before the street name (400 W OAK ST), while a post-directional follows the suffix (400 OAK ST W). They are not interchangeable: in many cities they point to different streets.

When the pound sign is fine

If you do not know the correct designator, USPS accepts the pound sign (#) followed by a space and the number, such as 22 HILL RD # 4. Put a space after the symbol so it is not read as part of the number.

Why this matters for developers

If your app lets people type "Street", "Str." and "ST" freely, the same address can appear three different ways. Mapping inputs to the standard abbreviations before saving is a small step that prevents a lot of cleanup later. Generated test addresses that already use standard abbreviations make it easy to check whether your normalization code leaves correct input unchanged.