The North American Union (NAU) is a theoretical economic union, in some instances also a political union, of Canada, Mexico, and the United States. While the concept can be viewed as loosely based on the European Union, occasionally including a common currency called the Amero or the North American Dollar, the union of the North American continent, and beyond that to Central and South America, has been the subject of academic concepts for over a century. One reason that it has not become a major subject of discussion is individual development in each region that failed to prioritize a larger union.