Nigeria accounts as the world's largest producer of yams, will other 45 million metric tonnes produced annually. In the course of transporting yams from one state in the country to another, retailers uniquely mark their yams to split costs. Thus, the burden of renting a trailer or van alone is minimized for each person. When the yams reach thier destination, each retailer can easily identify their yams. Yams are also very significant in traditional marriage customs of Nigeria. The exact number of yams required as dowry varies according to the tradition of each community or town. Some western states in Nigeria where yam tubers are produced in large quantities include Osun and Oyo.