Why do I sometimes lose access to trade nodes? E.g., For years I was transferring a ton of trade power from the lucrative Ivory Coast trade node, but after dismantling a part of Spain and suffering a major relations hit with them, I no longer have a merchant at this particular node....the tooltip says it's outside my range, which seems strange because this is very late game and I have colonies, trading posts, all over the world.
@SirGrotius - you seem to be on the 'political' mapmode in your screenshot - not the trade mapmode. The the supply ship range is slightly different to the trade range (though related). If it's out of your range, on the trade mapmode the node should have a checkerboard look.
You also seem to have all your merchants occupied. Is it possible that you've pulled a merchant to a new node from this one accidentally?
One last thing, you have all your merchants currently collecting trade from each node.
Sending as much trade to your home node (the one with your capital, or Main Trade City if you set otherwise) is usually the best strategy. You don't strictly need a merchant at your home node (you get a 10% buff to efficiency ) as you collect trade there automatically.
If you collect trade from your home node, and have all your merchants upstream 'transfer trade power' to your home node, you get a 10% bonus to trade power
per merchant.
With your 8 merchants that would be an 80% increase. Getting more merchants means you can stack even more.
Trade also increases in value when it is transferred, the effect declines after several nodes, but it is a real bonus.