The Mayors of the Mississippi River, in partnership with the United Nations Environment Programme, National Geographic Society and the University of Georgia, launch an initiative to combat plastic pollution along one of the world’s greatest waterways. It is estimated that up to 40% of plastic pollution entering the Gulf of Mexico, and then into the ocean, originates from the Mississippi River. Working with volunteer citizen scientists from local communities, the initiative will record data on the state of plastic pollution at key sites along the river. This data will be used to generate a ‘plastic pollution map’ that will help policy makers, business and citizens take action.