When they stand alone, names of geopolitical entities should be spelled in full. The abbreviation U.S. (which sometimes appears without spaces or periods) is an adjective, as in U.S. Fish and Wildlife Service. As a noun, spell it out ("wildlife conservation in the United States").
In lists, tables, and when combined in an address, the names of U.S. states, territories, and possessions may be abbreviated in standard ways (Table 5.4). The preferred form still is the conventional system. However, it is rapidly giving way to the two-letter postal code system specified by the U.S. government for use with zip-code addresses and shown here in parentheses. Whichever system you use, be consistent. Do not switch from one system to the other.
Was this article helpful?