The construction of binational hydroelectric plants on the Paraná River at Itaipú by Brazil and Paraguay and at Yacyretá and Corpus by Argentina and Paraguay reflects unprecedented cooperation and integration among these three nations, with far-reaching consequences for the future economic, social, and political development of all the Paraná River hinterland. The Paraná River Basin, or River Plate Basin, is among the five largest water systems in the world, second in size only to the Amazon Basin in the Western Hemisphere. With a length of 2,796 miles, it includes three main rivers, the Paraná, Paraguay, and Uruguay, and their tributaries. It covers an area of 1,980,000 square miles and contains a population estimated in 1980 at more than eighty million people. Brazil takes the largest share of the Basin at 45.9 percent; Argentina has 28.19 percent, and Paraguay has 13.1 percent, with the remainder held by Bolivia and Uruguay. Brazil's share of the basin comprises some of the relatively more progressive and industrialized southwestern, southeastern, and southern states of Mato Grosso, Goiás, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul. In Argentina, the provinces adjacent to the Paraná River contain 60 percent of the country's population and support 85 percent of its economic activity. Until the completion of a paved road and the international bridge over the Paraná River in the 1960s that permitted direct access to the Atlantic coast of Brazil, Paraguay's communication with world markets depended exclusively on the Paraguay and Paraná rivers.