A trade route manager, they're a huge pain to manage in the late game.

It would make the game go significantly quicker later on, and would also be a pretty awesome feature. Here's the idea I had for a window:

great idea! I think the first city selection is not necessary (or harder to implement, because switching cities takes a turn).

I would settle for some way to highlight the current route on reassignment prompt. Or just bring it to the top of the list (and autoscroll up). If it was an internal route show the internals first, if it was external, show intracolonial ones first...