Trade routes are established when you move a Caravan into another city, either one of your own at least ten map squares from the Caravan's home city, or a rival's city. The arrival of a Caravan results in an immediate payment of cash into your treasury plus the trade route. A trade route increases the trade generated by the Caravan's home city each turn thereafter, unless the connected city is destroyed. The value of a trade route is highest between a rival city on another continent, and increases with the size of both cities involved and the distance they are apart. Trade routes are essential to strong economies and large civilizations.
