When Britain gained formal control over what is now Guyana in 1814, it also became involved in one of Latin America's most persistent border disputes. At the London Convention of 1814, the Dutch surrendered the United Colony of Demerara and Essequibo and Berbice to the British. Although Spain still claimed the region, the Spanish did not contest the treaty because they were preoccupied with their own colonies' struggles for independence. In 1835 the British government asked German explorer Robert Hermann Schomburgk to map British Guiana and mark its boundaries. As ordered by the British authorities, Schomburgk began British Guiana's western boundary with Venezuela at the mouth of the Orinoco River. A map of the British colony was published in 1840. Venezuela protested, claiming the entire area west of the Essequibo River. Negotiations between Britain and Venezuela over the boundary began, but the two nations could reach no compromise. In 1850 both agreed not to occupy the disputed zone.

The discovery of gold in the contested area in the late 1850s reignited the dispute. British settlers moved into the region and the British Guiana Mining Company was formed to mine the deposits. Over the years, Venezuela made repeated protests and proposed arbitration, but the British government was uninterested. Venezuela finally broke diplomatic relations with Britain in 1887 and appealed to the United States for help. The British at first rebuffed the United States government's suggestion of arbitration, but when President Grover Cleveland threatened to intervene according to the Monroe Doctrine, Britain agreed to let an international tribunal arbitrate the boundary in 1897.

For two years, the tribunal consisting of two Britons, two Americans, and a Russian studied the case. Their three-to-two decision, handed down in 1899, awarded 94 percent of the disputed territory to British Guiana. Venezuela received only the mouth of the Orinoco River and a short stretch of the Atlantic coastline just to the east. Although Venezuela was unhappy with the decision, a commission surveyed a new border in accordance with the award, and both sides accepted the boundary in 1905. The issue was considered settled for the next half-century (see Relations with Venezuela , ch. 4; Guyana-Venezuela Dispute , ch. 5).

Data as of January 1992