Venezuela Boundary Dispute, diplomatic controversy, notable for the tension caused between Great Britain and the United States during much of the 19th cent. Of long standing, the dispute concerned the boundary between Venezuela and British Guiana (now Guyana); the Venezuelan claim, extending E to the Essequibo River (and thus taking in most of the settled areas of British Guiana) had been inherited from Spain, and that of Great Britain, stretching W to the Orinoco, was acquired from the Dutch in 1810.

The controversy did not gain importance until Great Britain in 1841 had a provisional line (the Schomburgk Line) run. Discovery of gold in the region intensified the dispute. Great Britain refused to arbitrate concerning the settled area; Venezuela, however, maintained that the British were delaying in order to push settlements farther into the disputed area. Venezuela sought aid from the United States and in 1887 broke off diplomatic relations with Great Britain. President Grover Cleveland's secretary of state, Thomas Francis Bayard, began negotiations, but the matter lapsed.

In 1895, Secretary of State Olney, invoking a new and broader interpretation of the Monroe Doctrine, virtually demanded arbitration, basing the right of the United States to intercede on the ground that any state whose interests or prestige is involved in a quarrel may intervene. Lord Salisbury, the British prime minister, offered to submit some of the area to arbitration but refused to allow British settlements to be submitted to adjudication. That reply, a rebuff to Olney, brought Cleveland's momentous message to Congress on Dec. 17, 1895, which denounced British refusal to arbitrate and maintained that it was the duty of the United States to take steps to determine the boundary and to resist any British aggression beyond that line once it had been determined.

The president's message caused a commotion; Congress supported him but, although there was some war talk, neither nation desired to fight. Salisbury, involved in European troubles and disturbed by difficulties in South Africa, sent a conciliatory note recognizing the broad interpretation of the Monroe Doctrine. An American commission was appointed, and the line that was finally drawn in 1899 made an award generally favorable to Great Britain. Venezuela has periodically revived its claims to the disputed land and offshore territory, most recently in under the populist presidents Hugo Chávez (2000) and Nicolás Maduro (2015).