A trade route is a link formed between a civilization's cities and its Image:Capital5.png Capital, which traders regularly use to move and conduct their trading. This might happen via land, using Image:Roads (Civ5).png roads, Image:Railroads (Civ5).png railroads, or via sea, using Image:Harbor (Civ5).png Harbors. A trade route is open with a city if one of the above-mentioned infrastructures is in place at the beginning of your turn.