What is the proper abbreviation for United States of America?

Use periods with the two-letter abbreviation for United States. Do not use periods with the three-letter abbreviation for United States of America. Use the abbreviation U.S. only as an adjective. Spell out United States when it is a noun.

• The U.S. government is one of the nation's largest employers.
• Most of their products were made in the USA.
• CU-Boulder is recognized as one of the premier public universities in the United States.