The Treaty of Guadalupe Hidalgo, which ended the Mexican War in 1848, designated the main channel of the Rio Grande as the Mexico-U.S. boundary. Disputes caused by frequent changes in the river's course led to the Treaty of 1884, which recognized only river diversions resulting from natural occurrences, and the International Boundary Commission was established in 1889 to administer that treaty. In 1906, the American Rio Grande Land and Irrigation Company dug an unauthorized canal about two miles south of here that altered the river's natural course, isolating a 419-acre section of U.S. property called El Horcon tract south of the river. Although still U.S. territory under the Treaty of 1884, the tract and the gambling and resort community of Rio Rico, which flourished there during the 1920s and 1930s, became increasingly subject to Mexican administration and jurisdiction. After the U.S. granted Mexico territorial rights over El Horcon tract and Rio Rico in 1970, a native of Rio Rico sued the U.S. government to guarantee his U.S. citizenship, beginning an eight-year legal battle that eventually led to U.S. citizenship for about 200 people born in Rio Rico before 1970.