It depends on the style guide you are following. You can use periods after "U.S." or omit them entirely, using "US." Both styles are acceptable; just maintain consistency.
Here's a breakdown:
-
With Periods (U.S.): This style is traditional and often preferred in academic and formal writing.
-
Without Periods (US): This style is more common in journalistic and informal writing. Many style guides, including the AP (Associated Press) style, now recommend omitting the periods because it is shorter and cleaner.
Key takeaway: The most important thing is to choose one style (either "U.S." or "US") and consistently use it throughout your writing. Don't mix the two within the same document.
