The Chamizal dispute was an international land and boundary conflict over contested land (estimates range from 600 to 1,600 acres [240–650 ha; 2.4–6.5 km2]) along the Mexico–United States border between El Paso, Texas, and Ciudad Juárez, Chihuahua.[1] The conflict was caused by multiple meandering, southward shifts in the Rio Grande, which delineates the U.S.-Mexico boundary in this region.[2] When the International Boundary Commission (IBC) first began investigating the dispute in 1895, it discovered that an 1852 survey of the international boundary/Río Grande (in Spanish: Río Bravo del Norte) through El Paso and Cd. Juárez was significantly different from the river's present (1895) location.[3] After much investigation, the IBC decided that the Chamizal Dispute began in 1864. That year the Río Grande made a dramatic, southward shift after a remarkable flood in the river. This shift subsequently placed Mexican territory known at that time as Paso del Norte’s “Partido Chamizal” or the “Chamizal District” north of the river/boundary—and seemingly into U.S. jurisdiction.[4] As the river’s southward meanderings continued, and as more Anglo American settlers began arriving to this region in the late 1880s and settling Partido Chamizal as part of the American town of El Paso, these processes together created the swath of contested land known as "El Chamizal" or the "Chamizal Zone." While Americans exerted control and jurisdiction over the territory, the state of Mexico never relinquished its claim to the zone. Residents of Cd. Juárez who had owned and farmed land within Partido Chamizal also never gave up their claims.
Over the many decades that followed, multiple efforts on the part of both Americans and Mexicans were made to resolve this conflict. Each time, these efforts failed. Tensions over the territory during the historic Taft–Díaz summit almost resulted in the attempted assassination of both presidents on October 16, 1909.
In 1961, in the midst of the Cold War and with worries over Mexico's potential allyship with Cuba mounting, U.S. President John F. Kennedy broached the idea of perhaps finally setting this conflict. Negotiations coalesced, in 1963, with the Chamizal Treaty, which was ratified in 1964. The settlement identified 630-acres in South El Paso as El Chamizal and promised to return this acreage to Cd. Juárez. The Chamizal Zone was officially ceded to and became incorporated into the Republic of Mexico on October 28, 1967. The Chamizal Treaty remains the first and only time the United States has given land back to Mexico.
The Spanish word "Chamizal" comes from chamizo or chamiza, the common name for the four-wing saltbush (Atriplex canescens) which covered the disputed land near the present-day park. It is a rather ordinary looking shrub that thrives in diverse soil and climatic conditions. The chamiza once grew prolifically in the Chamizal Zone because of the salty soil deposited by the river and the constant movement of this soil across the river’s alluvial plain. With roots reaching a depth of as much as 15 feet, the chamiza stabilized the soil and protected against eroding watersheds. With increased urbanization in both El Paso and Cd. Juárez through the 20th century, however, the once-prolific chamiza became increasingly scarce in the area.