Bolivia–Brazil border
A long line across the Amazon basin. Its northern part was redrawn in 1903, when Brazil took the rubber-rich Acre from Bolivia after an uprising by Brazilian rubber tappers, paying £2 million and promising a railway.
Written from cited sourcesLast checked 29 September 2026Suggest a correction
See it on the globe:Bolivia →Brazil →
A line nobody had surveyed
By the Treaty of Ayacucho of 27 March 1867, Brazil recognised the Acre lands as Bolivian, partly to keep Bolivia neutral in its war with Paraguay. West of the Madeira river the treaty ran the border along the parallel of 10°20′ south to the Javari river, though nobody had explored far enough to know where the Javari’s source was.[1]
In 1874 a Brazil–Peru commission put the Javari’s source much farther north, at 7°1′ south. The border was then drawn as a slanting line from the mouth of the Beni to that point, the “Tefé line”, instead of along the parallel, and a Brazil–Bolivia protocol of 1895 accepted it.[1]
Rubber and revolt
Brazilians, many from the drought-stricken northeast, moved into the Acre basin to tap rubber in the second half of the 19th century, with little regard for whose land it was.[1] Acre’s rubber was the best in Brazil, and the boom drew more and more migrants.[2] In 1899 a Spanish adventurer, Luis Gálvez Rodríguez, proclaimed an independent Republic of Acre, which soon collapsed.[2]
In 1901 Bolivia leased the region for 30 years to the Bolivian Syndicate, a group of mainly American and British investors, with full control of customs and security. Brazil closed the Amazon to shipping in response. On 6 August 1902 armed Brazilians led by Plácido de Castro attacked a Bolivian garrison on the Xapuri river, and the Bolivian forces surrendered on 24 January 1903.[1]
The Treaty of Petrópolis
Brazil’s foreign minister, the Baron of Rio Branco, insisted on reading the 1867 treaty literally, along the 10°20′ parallel, and offered to swap land for Acre or buy it. The Bolivian Syndicate accepted £114,000 to cancel its contract, and Bolivia agreed on 21 March 1903 to Brazilian administration while a treaty was negotiated.[1]
Under the Treaty of Petrópolis, signed in 1903, Bolivia ceded Acre in return for land at several points along the border, free transit to the Atlantic, a Brazilian promise to build the Madeira–Mamoré railway, and £2 million because the swapped areas were not equal. Brazil gained about 191,000 km².[1] Acre was later organised as a territory and became a Brazilian state in 1962.[2]
Timeline
186727 March 1867
Treaty of Ayacucho
Brazil recognises the Acre lands as Bolivian.[1]
1874
Tefé line
A survey places the Javari’s source far north, and the line slants.[1]
1899
Republic of Acre
Gálvez proclaims a short-lived independent state.[2]
1901
Bolivian Syndicate
Bolivia leases Acre to foreign investors.[1]
19026 August 1902
Acre revolution
Plácido de Castro’s men attack a Bolivian garrison.[1]
190324 January 1903
Bolivian surrender
The Bolivian garrison surrenders to Plácido de Castro.[1]
1903
Treaty of Petrópolis
1962
Statehood
Acre becomes a Brazilian state.[2]
More borders
Sources
- [1]O Tratado de Petrópolis: interiorização do conflito de fronteiras (Flávia Lima e Alves) · Revista de Informação Legislativa, Senado Federal (Brazil) · 2005
- [2]Acre (state, Brazil) · Encyclopaedia Britannica (Wayback Machine copy)
Map geometry from Natural Earth via world-atlas. See credits.