If the U. S. National is in use by the Armed Services or Federal Government, the tradition is to fold the U. S. National in a triangle, for ceremonial purposes. However, it is not necessarily a tradition for the citizens of the U. S. to do so. The U. S. flags that fly over the White House and presented to someone by members of Congress are not folded in a triangle, a square, usually received in the same box of the manufacture of the flag.
The individual States of the U. S. do not fold their State flags in a triangle, a rectangle is fine or other respectful treatment. A Confederate flag or other Nations flag should also be folded with respect.
The U. S. Flag represents the citizens, first, the Government second.
Happy Trails!
Tom Martin
www.Confederate-flags.org