In Washington, on 20 March 1905, the United States and Mexico sign the Convention Between the United States and Mexico for the Elimination of the Bancos in the Rio Grande from the Effects of Article II of the Treaty of November 12, 1884 (the Banco Convention of 1905). The plenipotentiaries are Alvey A. Adee (United States) and Manuel de Azpíroz (Mexico); the authentic texts are English and Spanish.

The 1884 Convention kept the boundary on the abandoned channel after sudden (avulsive) changes. On the Rio Grande, cut-off meanders formed “bancos”—tracts ringed by the old bed—that stayed under the sovereignty of the country on the opposite bank even after the river moved, producing property and jurisdiction disputes.

Article I removes the fifty-eight bancos already surveyed (engineers’ report of 30 May 1898) from Article II of 1884: bancos on the right bank pass to Mexico, those on the left to the United States, along the deepest channel. Later articles govern future bancos under 250 hectares and under 200 inhabitants, and protect property and residents’ rights.

The U.S. Senate advises ratification on 28 February 1907; ratifications are exchanged at Washington on 31 May 1907; proclamation follows on 5 June 1907. A protocol of 14 November 1905 completes the signature of maps omitted on 20 March.

From 1910 to 1976 the International Boundary and Water Commission applies the convention in 247 banco exchanges on the Rio Grande (and, from 1927, on the Colorado), transferring tens of thousands of acres between the two countries.

The Banco Convention of 20 March 1905 remains the instrument that aligned the U.S.–Mexico river boundary with the living channel by taking bancos out of the rigid 1884 regime.

Image: Rio Grande; Wikimedia Commons. Cropped to 16:9.

Source consulted: Banco Convention of 1905. Treaty text: Text of the Banco Convention of 1905 (NPS Chamizal).