Okay, here's what I see after a very quick, unthorough glance:
1.) You have sizable stacks of military units inside your cities. They are doing nothing there but eating up your gold and slowing your research down. Either disband them to free up gold, or send them out to clear Barbarian settlements, or -- best of all of course in my opinion -- put them in boats and go do to the Byzantines what you did to the Spanish.
2.) Speaking of which, your navy should be a lot bigger. And you have Astronomy, so why do you still have Galleys? Build Caravels, and quickly.
3.) Valencia is building a Coliseum. The only time you should EVER build a Coliseum is if you are going for a 1 City 20K Culture win.
4.) You do not have nearly enough workers. While some people might say that an Industrious Civ (like America) can get away with having fewer workers, and this is somewhat true early on, let me put it this way. The Americans are Expansionist and Industrious. What two units do these traits effect? Scouts and Workers. Not building these units and using them is basically taking your strengths away from yourself. Since you're no longer in the Ancient Era you don't really need to bother with Scouts anymore, as they can no longer give you easy technology gains from goody huts. So that means you're down to workers. Build LOTS. Americas Civ strength is its faster working workers. Build them. Use them.
5.) Also, you need a lot more cities, and closer together too. Several reasons for this. A) The more cities you have, the more unit support you will have. This is doubly true when you are in Republic (which is good, 90% of the time you want to get in to Republic ASAP and stay there). B) You did all that hard work to conquer all that land and eliminate your rivals on your continent. It's all yours. Start using it! The AI civs on the other continent are going to start swarming in with settlers and start scavenging what you yourself have killed and earned. C) Population is power in Civ. The more cities you have also means the more commerce you will generate per turn, ergo the more money you will have and the faster you will research. D) With America it is especially true that bigger = better, because again, by the time America's UU shows up in the tech tree the game is usually already over. So your military is going to be made up entirely of normal units. Since you don't have an unfair advantage on an individual level, your unfair advantage needs to come from having a whole lot MORE military units than the tribes you're about to start conquering (especially the ones in the Industrial Age. They'll have riflemen. You'll see what I mean
).
6) No. Seriously. Fill up that continent with your cities. Don't be afraid to let cities overlap their radiuses. In fact, it's better to have them overlap. It took me quite a while to figure that out. Especially with America, quantity is better than quality. So, in terms of unit support, a size 7 city is equal to size 12. So, as far as the whole of your empire is concerned, ten size 7 cities is better than five size 12 cities. Also, since you're still in the Middle Ages, you do not have the technolgy to get your cities above size 12. And, in fact, once you do have that technology, you'll notice that size 13 and above cities start polluting. This is a disincentive to go above 12. All the more reason to pack your cities in tightly and let them overlap some; they don't need 20 tiles, they each only need
12. Or maybe even just 7. (As an added bonus, it is easier to keep a size 7 city from rioting than a size 12. You'll be able to lower your luxury rate, which will in turn let your tax and science go higher). Oh, and while I'm at it, if you have to make one citizen be a specialist to keep a city from rioting, try to have them be a Taxman or Scientist instead of an Entertainer.
If you have a size 12 city, it doesn't need a granary anymore. It can't grow anymore, so a city building that speeds growth is a useless drain on your cash supply.
Cities should be 3 or even just 2 tiles apart. If you'v ever seen CxxxC or CxxC on this message board, this is what it means. The capital C's are city squares and the x's are the tiles between them.
7.) A common phrase around here is "your cities don't need anything. What does YOUR EMPIRE need your cities to have?" If you're building libraries and temples and coliseums all over the place, you're probably doing what I did early on; leaving each city on its own to take care of itself. This is another way in which you are hamstringing yourself, handicapping your empire, and letting the AI outresearch you on Warlord. It is important -- especially early on, but still even at this point in the game that you're at -- to let your cities specialize. Let one concentrate on building settlers. Let one concentrate on building workers. Although at this stage of the game I'd recommend at least two of each so you can fill up all that land of yours before the AI starts trying to steal it from you. At least one of your coastal cities, perhaps even more, should be building caravels. Especially if you're planning to invade the other continent, as you'll need boats to get your military from where it is to where it should be -- on foriegn soil, wreaking havoc. And on that note, the rest of your cities should be building military units (ALL unit producing cities should have barracks. All cities not producing military units no longer need barracks. Sell them off). Don't have each city try to do everything for itself. It's like trying to manage a bunch of tiny one-city civs at once. Let each city specialize.
8.) Did having the Statue of Zeus and the Ancient Cavalry cause you to shy away from researching Metallurgy? Don't be afraid of it. You'll get cannons, which you will probably need if you're going to invade, and on that same note, your Ancient Cavalry aren't going to be much use against enemies that have Rifelmen defending. Your ancient Cavs are still good enough to deal with dispersing barbarians, and you've got enough of them to take care of that job. After Metallurgy comes Military Tradition, and the Cavalry Unit. This will still have major problems against the French and Zulu, who will have riflemen, but the Cavalry at 6.3.3 will rip through the other medival civs, such as the Byzantines....
9) Which brings me to what will be my last point for now. Pointy Stick Research. You know what's a great way to catch up to the AI who is outresearching you? Beat 'em up. Think of it as mugging them for their technology. Raze a few cities and they will be "convinced" to share their technology with you in exchange for you not hurting them anymore (which has the added bonus of slowing down their research from that point onward, letting you catch up). The quicker you do this, the better. It will be a lot easier when you have Military Tradition an Cavalry, but a lot harder once they have Nationalism and Riflemen. That's your window. Build some boats and get to it before it closes.
10) I didn't check all your cities in depth. But, I did look at San Francisco. That's been built pretty well. I like it. Size 7, and that was a good city to build a Courthouse in. (Some cites, the ones furthest from your capital, will be so corrupt even a Courthouse can't help them). It's on the water, too. In fact, that would be a good candidate for a city to commit to producing Caravels if you're going to invade the other continent (and obviously from my post here I, as a warmonger myself, am clearly assuming you intend to do
).
11.) You're researching Democracy. As soon as you've got it, check around to see what techs you can trade it for. Check on every civ to see how much you can get from each one for it, then take the best deal. I do not recommend actually revolting and switching over to Democracy, though. You're already in Republic, which is a good place to be.
I might have more tips after taking another, closer look at your game. But, a picture is worth a thousand words, and a posted save is worth even more than that. Checking Tone's save file of what he did with your game will likely say more and say it better than I have.
However if you want to play a few more games with the Americans, then do that. If you enjoy them, that's all that counts. Anyway, I actually think that it's wise to play a few games with the same civ so that you can learn how to play them to their strengths.
