Defined the southern Portugal-Spain border along the Guadiana River, while leaving a northern section undemarcated to this day.
Key Facts
- Date signed
- 29 June 1926
- Signing city
- Lisbon, Portugal
- Border section demarcated
- Ribeira de Cuncos confluence to Guadiana estuary
- Undemarcated section
- Caia confluence to Ribeira de Cuncos confluence
- De facto border in undemarcated area
- Guadiana River
Location
Cause → Event → Consequence
Portugal and Spain had a long-standing need to formally delimit their shared border along the Guadiana River. The southern stretch, near Olivenza and extending to the river's estuary, lacked a precise legal demarcation, creating ambiguity in the boundary between the two Iberian nations.
On 29 June 1926, Portugal and Spain signed the Convention of Limits in Lisbon, formally demarcating the border from the confluence of the Ribeira de Cuncos with the Guadiana, just south of Olivenza, southward to the Guadiana River estuary.
The agreement resolved the legal status of the southern portion of the Guadiana border. However, the section between the Caia River confluence and the Ribeira de Cuncos confluence was not addressed and remains undemarcated, with the Guadiana River serving as the de facto boundary in that stretch.
Political Outcome
Southern Guadiana border officially demarcated; northern section remains undemarcated with Guadiana as de facto boundary.