The Chamizal dispute was caused by a shift in which one of the principal rivers in the southwest United States and northern Mexico?
Rio Grande The Rio Grande ( or ; Spanish: Río Bravo del Norte , ] or simply Río Bravo) is one of the principal rivers in the southwest United States and northern Mexico (the other being the Colorado River). The Rio Grande begins in south-central Colorado in the United States and flows to the Gulf of Mexico. Along the way, it forms part of the Mexico–United States border. According to the International Boundary and Water Commission, its total length was 1896 mi in the late 1980s, though course shifts occasionally result in length changes. Depending on how it is measured, the Rio Grande is either the fourth- or fifth-longest river system in North America.
Pima Villages Pima Villages, sometimes mistakenly called the Pimos Villages in the 19th century, were the Akimel O’odham (Pima) and Pee-Posh (Maricopa) villages in what is now the Gila River Indian Community in Pinal County, Arizona. First, recorded by Spanish explorers in the late 17th century as living on the south side of the Gila River, they were included in the Viceroyalty of New Spain, then in Provincias of Sonora, Ostimuri y Sinaloa or New Navarre to 1823. Then from 1824 to 1830, they were part of the Estado de Occidente of Mexico and from September 1830 they were part of the state of Sonora. These were the Pima villages encountered by American fur trappers, traders, soldiers and travelers along the middle Gila River from 1830's into the later 19th century. The Mexican Cession following the Mexican American War left them part of Mexico. The 1853 Gadsden Purchase made their lands part of the United States, Territory of New Mexico. During the American Civil War they became part of the Territory of Arizona.