United States Flag Code

Although the Flag Code is U.S. Federal law,
there is no penalty for failure to comply with the Flag Code and it is not widely enforced

Though not part of the official Flag Code, according to military custom flags should be folded into a triangular shape when not in use - Folding the US Flag

On June 14, 1923, the National Flag Code was constructed by representatives of the Army, Navy, and other groups.