There is no documented reason for the choosing of those colors for the flag. Probably what ol' Betty had laying around. It was said that Washington choose red due to the Brit colors, but now written down anywhere.The colour red can indicate a variety of things such as passion,rage,warning,blood,sacrifice, etc. The colour red was chosen for the American flag to symbolize sacrifice and courage. Therefore it isn't much of a stretch to assume the colour's meaning is the same as back then.
