I think that the flag stands for their COUNTRY or REPUBLIC.
Francis Julius Bellamy wrote the original version of the American Pledge of Allegiance.
It stated with this sentence:
"I pledge allegiance to my Flag and to<span> the Republic for which it stands, one nation, indivisible, with liberty and justice for all" </span> The flag stands for the Republic. The Nation they all fought hard to free from their British colonizers.