The flag of the United States is made to specific proportions,
therefore we can always fold it the same unique way and it will
come out the same, no matter what size it is.
Steps
:
1.) To properly fold the Flag, begin by holding it waist-high
with another person so that its surface is parallel to the ground
:

2.) Fold the flag in half
twice, width-wise :
1st Fold:

2nd Fold:
3.) Beginning at the striped end,
fold one corner into the opposite side of the flag, forming a
triangle :

4.) Repeat this triangular
folding until only a small strip of the star field shows :

5.) Tuck this strip into the triangle :

Tips:
Keep the flag from touching the ground while folding. When making
the two width-wise folds, be sure to keep the stars on the outside.
If you do this, you will have a triangular field of stars when
you are finished folding the flag.