A more thorough explanation:

U.S.

U.S. is an abbreviation that can stand for two things:

1. United States: This refers to the country located in North America, consisting of 50 states and various territories. For example, "I am a citizen of the U.S."
2. UNITED STATES REPORTS: This refers to a series of books that contain the official opinions of the Supreme Court of the United States. For example, "The case was published in volume 500 of the U.S. Reports."

Examples:

• "I am proud to be from the U.S."
• "The U.S. Reports are an important resource for lawyers and judges."

The first example illustrates the use of U.S. to refer to the country. The second example illustrates the use of U.S. to refer to the series of books containing Supreme Court opinions.