The 1905 Banco Convention established a bilateral mechanism for the U.S. and Mexico to exchange enclaves formed by river channel shifts along their shared border.
Key Facts
- Signed
- 1905
- Ratified by both nations
- 1907
- Banco exchanges completed
- 247 exchanges
- Period of exchanges
- 1910–1976
- Extended to Colorado River
- 1927
By the Numbers
Location
Cause → Event → Consequence
The Rio Grande's rapid erosion and frequent channel shifts created bancos—parcels of land isolated by river cutoffs—that left territory ambiguously assigned between the United States and Mexico, generating recurring border disputes that existing agreements could not efficiently resolve.
Negotiated and signed in 1905, then ratified by both nations in 1907, the Banco Convention established a formal procedure by which the two governments could exchange these isolated land parcels, chiefly in the Lower Rio Grande Valley, the Presidio Valley, and the El Paso–Juárez Valley.
Between 1910 and 1976, the convention facilitated 247 banco exchanges, resolving numerous localized sovereignty ambiguities. In 1927, its scope was extended to the international segment of the Colorado River, broadening its application beyond the Rio Grande.
Political Outcome
Bilateral framework established for exchanging river-formed enclaves; 247 banco exchanges completed 1910–1976; extended to the Colorado River in 1927.