Quote Originally Posted by Oaty View Post
I think a land route doesn't require an open trade route but will use you your current and future trade routes, so you can't open sea trade route until you have more trade routs open then used
No, this is not right. In my UP game, I was unable to create more than 3 sea trade routes due to the size of my only European trade port. When I noticed this, I set about a plan to capture another province with a trade port, but that was going to take a while. In the meantime, I opened up land trade routes with 2-3 other adjacent factions. By your account, this would have required me to get an extra 3-4 trade route slots via ports before I could open another one. This is not what happened. I eventually got my extra trade slots by spawning a new port town and building it into a commercial port. As soon as the most primitive level of port was ready, I was instantly able to open new sea trade routes, even though my land trade routes had increased while I was previously capped.