Saint Croix is an island in the Caribbean Sea, and a county and constituent district of the United States Virgin Islands (USVI), an unincorporated territory of the United States. The island was a possession of France from 1650 until 1733. On June 13, 1733, France sold the island group to the Danish West Indies Company. For nearly 200 years, the islands were known as the Danish West Indies. St. Croix and the Danish West Indies were sold to the United States by Denmark in the Treaty of the Danish West Indies of 1916, in exchange for a sum of US$25,000,000 in gold. In a national referendum 64.2% of Danish voters approved the sale. An unofficial referendum held in the islands resulted in 99.83% vote in favor of the purchase.