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.
Pasión River The Pasión River (Spanish: Río de la Pasión , ] ) is a river located in the northern lowlands region of Guatemala. The river is fed by a number of upstream tributaries whose sources lie in the hills of Alta Verapaz. These flow in a general northerly direction to form the Pasión, which then tends westwards to meet up with the Salinas River at . At this confluence the greater Usumacinta River is formed, which runs northward to its eventual outlet in the Gulf of Mexico. The Pasión River's principal tributaries are the San Juan River, the Machaquila River, and the Cancuén River.