Sorry! Slipped my mind. Should be there now.
Plus roads to Ai for trade routes.
Ah, you need roads to trade. Gotcha.
What I'm saying is that your basic empire management could be improved a lot!
They absolutely could, which brings me to...
So, per Gumbolt suggestion, I started another game in parallel with this one. And I've discovered quite a few things!
One of my earliest mistakes was spacing out cities (I.E. no overlap between them) and settling my first cities far away. The rational being that forward settling will give me breathing room and that it will max out efficiency of each cities. That's not how it works.
You will almost certainly never have enough population to work every single tile in a city and -if you're playing the game properly- you shouldn't have gigantic population.
Early game you need to settle helper cities. I thought that every single city needed a food source or at least a couple of farms to be be viable. Again. no. First of all cities can grow fine with one food source, or even no food sources, provided that they have either grassland, or water tiles. Second, helper cities aren't meant to grow big. Of course, if they can (like the corn city in the Shadow game), great! If not, that's fine, because that's not their main function. They're meant to help work tiles of whatever city they're near and make money.
Here's how that game is going, by the by.
I'm getting amazing insight from this shadow game! Will update it soon(-ish)!