Wagon Trains is a social policy in Civilization V. It is part of the Commerce tree. Keeping the transport infrastructure in good shape is paramount for good trade. But throughout the centuries few innovations have had a more beneficial effect on trade than establishment of organized wagon trains - large groups of cargo carts accompanied by replacement animals, guards and supply loads, which are able to stop at pre-established post stations to rest and resupply on-the-go. As a result, not only were trade caravans able to trade more effectively, but they also damaged the roads much less.