During the slave days, the islands cultivated cash crops to earn money. In 1848, the governor granted the slaves emancipation, which was against the wishes of Danish Crown and devastated the economy of the islands. In 1917, a treaty was concluded in which the United States purchased the islands for $25,000,000.
The economy was boosted in the 1970s due to tourism and manufacturing.
The islands also receive cross-over subsidies, which generated approximately $100 million for the Virgin Islands in 2008.
The tourism industry is the main industry, generating 80% of GDP and employment. The majority of tourists are from the USA and the most common way to get there is by sea. The tourism industry mostly employs those who have migrated to the U.S. Virgin Islands. In 2005, a record of 2.6 million tourists visited.
Manufacturing industries developed significantly in the 1970s, especially on St. Croix island. Most industries depend of tax concessions and the financial advantages they derive from being a U.S. territory. An alumina factory processed bauxite until December 2009. The Hovensa oil refinery produced 495,000 barrels per day (78,700 m3/d), and closed down in February 2012.
According to the Virgin Islands' Department of Labor, the size of the local workforce is almost 50,000 people. In 2009, it was reported that the unemployment rate was 7.8%.Hovensa was also a large-scale employer after the government of the Virgin Islands.