I would personally advise goods transportation to be fully automated otherwise this will be unbearably tedious in the later stage. I keep only one or two diligences for special "one shot" needs but not more than that. After multiple tests about how to manage my trade routes, here's the system I've found to be the most efficient: I generally define "hub" colonies. Their number should be limited (let's say 1 for 10 cities) as that makes things a lot easier to manage. They are in most cases seaports. My carts only connect a single city to a single hub. Operating only one cart per city should be enough and I name them as the city they serve. That's very convenient to figure out what's going on. Similarly I name my ships as the hub port they serve (so that would be Jamestown I, Jamestown II, Jamestown III and so on). The hub requires to be able to handle massive quantities, that's why those are usually seaports as you can move goods out to Europe. Later in the game, my purpose is to get all goods available in the hub cities, so that I could serve other colonies with what they need. With a bit of thinking, you can feed pretty well the domestic market this way and makes tons of money. So, usually, my carts export the local production out of the city and import from the hub what is needed. I would classify import needs in 3 categories: buildings requirement (tools or stones) if the city doesn't produce its own. productions input: that can be sailcloth and ropes if my city builds ships but it can also be other things as well. domestic market service: getting goods in the city to feed its domestic market (something which is very profitable by the end of the game). The trade route system actually works really well to do all that. It can be tedious to set up though, as you need to really take the time to think about it, but once done, it runs fully automatic. I don't know if that will help you @smallfry, but that would be my 2 cents.