The basic concept is that if/when American begins to colonize other worlds, administering them requires a greater decentralization of the federal government on Earth, forming a Four Tier Republic:
2) Planetary (Commonwealth)
Thus we have the first twelve flags of America's 27 Planet Republic, the Commonwealths of the Inner Planets, i.e, planets no more than 20 LY from Earth.
*Earth: Humanity's Cradle World, and the home of the US Capitol. Like most countries it is the single most populated planet by the US.
*Mars: Often called Humanity's Second Home, Mars was the first planet terraformed by humans. It is home to seven US States, and has a society nearly identical to that of Earth.
*Venus: The second world to be terraformed by Humans, Venus is a hot tropical world, with a population residing closer to the poles. Like Mars it is societally identical to Earth.
*Atlantis was the first extrasolar colony of humans, and has a surface 95% covered in water. Its population has become largely defined by its seafaring culture, as most cities are actually built on the water itself for need to conserve land based resources.
*Lewis and Clark: Twin worlds in a single system, These two planets are almost exactly the same in mass and density, with near identical climates. They orbit on opposite ends of a single star, and are populated largely by former Virginians and New Englanders.
*Avalon: A lush and plentiful world, Avalon has become one of the most prosperous colonies of mankind. Its American population is largely from Pacific North West, however some from the Appalachians have also made a home there.
*Plymouth: Founded exclusively by the US, Plymouth is populated almost entirely by New Englanders.
*Omaha: Founded in a Joint American/European Expedition, Omaha was largely established by former military members. Today it is largely known as the primary off-Earth ship and weapons manufacturer and home to the two largest military bases for the EU and the US.
*Lincoln: Founded largely by Midwesterners, Lincoln is a peaceful, scholarly world, defined by great universities and agribusiness.
*Arcadia: Founded by Anglo-Europeans as a farming colony, Arcadia has become the chief US Supplier of high quality wines, beers, Kobe Beef, and Leafy Greens.
*Rhea: One of the few "Earth Twins" to have no intelligent life of its own, Rhea's American Population owe their success to the study of its unique flora and fauna by the hordes of naturalists, geneticists, and xenobiologists it produces and attracts. It was first founded by former associates of the Smithsonian Museum of Natural History.
The Outer Colonies
Future Old Glory
Firstly, is that "2066" underneath the Federal flag the date??? Holy crap, is FTL invented tomorrow in your timeline?
Speaking of FTL, this whole thing assumes that it exists--along with some sort of antigravity and/or reactionless drive--and is hella quick; after all, a colony isn't going to remain part of the US if it takes twenty years to get a message back and forth. Not to mention the whole concept of importing beef from another star system--rocket fuel is expensive, so obviously they're using something other than that.
As for planets orbiting opposite each other (in the same orbit, I presume that means), that's not exactly the most stable of formations. It would be better for them to be a double-planet or two planets in the habitable zone of the same star or something.
So the colonies are being saddled with shipload after shipload of refugees. Okay, I can buy that. But FTL technology is still brand spanking new--remember what the first generation of iPod and Xbox was like? Hell, the first steam engine probably needed to be shut down and restarted constantly, as well! FTL is magic, of course, so you can have it work however you like, but I think it would snap suspension of disbelief in half if the first starships work perfectly the first time like they were handed down to us from the archangels--if they have to do that, might I suggest finding them in some alien ruins on the moon or something? We're talking something that's not even theoretically possible here, after all--not by a long shot--and you have it happening before most of us picture us having a moon base, after all.
Aliens or no aliens and disaster or no disaster, I'd stretch out the time frame to a few centuries. I mean, we're talking less than thirty years between first touchdown and "present" and you have each colony having a fully-established cultural identity. Probably much less. And I noticed a map of a fully-terraformed Mars that seemed connected, which isn't happening this century.
Anyway, lovely job on the flags
Have you tried the Rhea flag with a blue field?
BTW, nice touch with Edwardsian Populism
-the internet will streamline a lot of economic processes, as well as decentralize a lot of stuff
-a surplus of resources thru-out the solarsystem will have an impact on the global economy likely similar to the crisis caused by spanish gold surplus from the new world
-a lot of the programs that seem necessary for populism to work, that dictated by FDR's bill of economic rights, would need a MASSIVE investment. the surplus of $ i mentioned above could likely cover this, but i dunno.
*just some stuff to think about*
-good luck with everything!
Empires used to last for centuries, but information flow was slower back then.