I'm no vexillologist, but I felt compelled to redesign the flag of the United States of America for some reason.
The "bars", which represent USA's first thirteen colonies, have been minimized. Origin stories are important but I'm more interested in the current state of the USA and its hopes for the future.
The "stars," which represent all 50 of the USA's current states, are still based around a five-pointed shape -- which we Americans are really fond of -- but have been turned into diamonds (which are simpler and easier to "read" from a distance) clustered around a common center to signify unity without compromising autonomy. E pluribus unum. Kinda gives it a United Nations sorta feel, which I like.
The aspect ratio is also 2:3 instead of the current 1:2, because that's what most countries use and I think it'd be nice to have us fit in better with the international community.
I also changed the navy blue to a more royal blue, because I really don't like navy blue.