2Checkout offers support for both standard and ZIP+4 ZIP codes.
Standard US zip codes
The standard zip code notation used by the United States Postal service uses five digits to identify a delivery area.
An example of a standard US zip code is 90210.
In addition to the classic five-digit zip codes used in the United States, 2Checkout also supports the use of ZIP+4 add-on zip codes, important when shipping physical goods.
The ZIP+4 system uses the basic five-digit code together with four additional digits to identify a geographic segment located within a five-digit delivery area. The segment can be a city block, a group of apartments or other mail receiving units that could benefit from the use of an additional identifier.
An example of a ZIP+4 zip code is 99577-0727.