It seems like America is still too weak, and it's because you improved their unique units rather than actually improving the civilization. Minuteman exists for a very short time before getting replaced, making it not important. The same problem exists for the B17, which can't upgrade (without mods) but still is inferior to the Stealth Bomber that isn't acquired long after. Adding bonuses to their units does nothing to actually improve the lackluster civilization. You need to upgrade the leader bonus.
And you did do that, but what you did wasn't important. You increased the cost reduction for buying tiles, but that always seemed unimportant to me. Buying tiles seems so rarely useful. For me, cities tend to grow in size faster than population anyway, and all those new tiles you can buy are worthless without people to work them.
My take? Leave the unique unit bonuses because they barely matter anyway, but switch the unique bonus to +1 sight and movement for land units and -25% gold cost for buying tiles. Manifest Destiny was all about exploring and spreading as quickly as possible. I was amazed that increased movement wasn't a part of it in the base game. It makes too much sense. Increased movement is also a decently powerful ability, making the civilization actually useful to play. They can explore, defend, or attack more rapidly. It's still not as strong as some other civilizations, but with increased movement America would no longer be the weakest civ in the game like it is now.
And you did do that, but what you did wasn't important. You increased the cost reduction for buying tiles, but that always seemed unimportant to me. Buying tiles seems so rarely useful. For me, cities tend to grow in size faster than population anyway, and all those new tiles you can buy are worthless without people to work them.
My take? Leave the unique unit bonuses because they barely matter anyway, but switch the unique bonus to +1 sight and movement for land units and -25% gold cost for buying tiles. Manifest Destiny was all about exploring and spreading as quickly as possible. I was amazed that increased movement wasn't a part of it in the base game. It makes too much sense. Increased movement is also a decently powerful ability, making the civilization actually useful to play. They can explore, defend, or attack more rapidly. It's still not as strong as some other civilizations, but with increased movement America would no longer be the weakest civ in the game like it is now.