Britain, the United States, and the Danish West Indies, 1916-17

The islands of St. Thomas, St. Croix and St. John are surrounded by Puerto Rico—once a Spanish colony—and the British Virgin Islands. Between the early eighteenth century and the early twentieth, the three main islands, combined with smaller minor islands in the surrounding archipelago, formed a single Danish colony: the Danish West Indies. In March 1917, sovereignty over the Danish West Indies was transferred from Denmark to the United States. This was because the Americans had purchased the islands for $25 million (the most they had ever spent on new territory) and, in doing so, created the territory of the US Virgin Islands.