The northern part of the Gran Chaco is partly wooded and swampy, and as the slope eastward is very gentle and the rivers much obstructed by sand bars, floating trees and vegetation, large areas are regularly flooded during rainy seasons.
The Buenos Aires treaty of the 3rd of February 1876 fixed the frontier between Argentina and Paraguay, and assigned to Paraguay the portion of the Gran Chaco between Rio Verde and Bahia Negra; the appropriation of the portion between Rio Verde and the Pilcomayo was submitted to the arbitration of the president of the United States, who in 1878 assigned it to Paraguay.
Carranza, Constitucion Nacional y Constituciones Provinciales Vigentes (Buenos Aires, 1898); Angelo de Gubernatis, L' Argentina (Firenze, 1898); Meliton Gonzales, El Gran Chaco Argentino (Buenos Aires, 1890); John Grant & Sons, The Argentine Year Book (Buenos Aires, 1902 et seq.); Francis Latzina, Diccionario Geografico Argentino (Buenos Aires, 1891); Geographie de la Republique Argentine (Buenos Aires, 1890); L' Agriculture et l'Elevage dans la Republique Argentine (Paris, 1889); Bartolome Mitre, Historia de San Martin y de la Emancipation Sud-Americana, segun nuevos documentos (3 vols., Buenos Aires, 1887); Historia de Belgrano y de la Independencia Argentina (3 vols., Buenos Aires, 1883); Felipe Soldan, Diccionario Geografico Estadistico Nacional Argentino (Buenos Aires, 1885); Thomas A.
The western section forms part of the great plain called the Gran Chaco (see Argentina), and is to a large extent unexplored.