The onset of World War I brought the reforms to a close and again left the islands isolated and exposed. During the submarine warfare phases of the First World War, the United States, fearing that the islands might be seized by Germany as a submarine base, again approached Denmark with a view to buying them. After a few months of negotiations, a selling price of $25 million (This is equivalent to $426,000,000 in 2010 dollars) was agreed. At the same time the economics of continued possession weighed heavily on the minds of Danish decision makers, and a bipartisan consensus in favor of selling emerged in the Danish parliament. The Treaty of the Danish West Indies was signed in August 1916, with a Danish referendum held in December 1916 to confirm the decision. The deal was finalized on January 17, 1917, when the United States and Denmark exchanged their respective treaty ratifications. The United States took possession of the islands on March 31, 1917 and the territory was renamed the Virgin Islands of the United States. U.S. citizenship was granted to the inhabitants of the islands in 1927. US wanted to have these Islands to command the Anegada Passage into the Caribbean Sea, a strategic point on the defense perimeter of the Panama Canal. Water Island, a small island to the south of Saint Thomas, was initially administered by the U.S. federal government and did not become a part of the U.S. Virgin Islands territory until 1996.

• Denmark..........................................30 Mar 1666 - 31 Mar 1801 with...
• Great Britain on St. Croix..............................1642 - 1650
• Spain on St. Croix.............................................1650
• France on St. Croix.....................................1650 - 1651
• The Knights of St. John (Malta) on St. Croix............1651 - 1665
• France (Proprietary 1665-1674) on St. Croix.............1665 - Jan 1696
• St. Croix became uninhabited from Jan 1696 to 1733. Brandenburg leases a factory on St. Thomas from Denmark on 24 Nov 1685; administered by the Brandenburg African Company (from 1701-1715, Royal Prussian African Company). This company existed till 1735. St. Croix was once again came under the rule of Denmark in 1734 and it became part of Danish West Indies in 1756.
• Great Britain....................................28 Mar 1801 - 19 Feb 1802
• Denmark..........................................19 Feb 1802 - 21 Dec 1807
• Great Britain....................................21 Dec 1807 - 20 Nov 1815
• Denmark..........................................20 Nov 1815 - 31 Mar 1917
  • Oldenborg dynasty
  • Frederik VI S/o Christian VII...............20 Nov 1815 - 03 Dec 1839
  • He was King of Denmark since 13 March 1808. King of Norway 13 March 1808 - 17 May 1814. Frederick reigned over Denmark for a total of 55 years; 24 years as crown prince regent since 1784 and 31 years as king. He lost Norway after his defeat in the Napoleonic Wars in 1814.
  • Christian VIII S/o Frederik.................03 Dec 1839 - 20 Jan 1848
  • He was the eldest son of Hereditary Prince Frederick of Denmark and Norway and Duchess Sophia Frederica of Mecklenburg-Schwerin. Treaty of Kiel had forced the king to cede Norway to the king of Sweden. He was elected Regent of Norway by an assembly of notables on 16 February 1814. He became King of Norway 17 May - 10 October 1814. Norway personal union with Sweden on 04 November elected Charles XIII of Sweden as the new king of Norway.
  • Frederik VII Carl S/o Christian VIII.......20 Jan 1848 - 15 Nov 1863
  • He was the last Danish monarch of the older Royal branch of the House of Oldenburg and also the last king of Denmark to rule as an absolute monarch. During his reign, he signed a constitution that established a Danish parliament and made the country a constitutional monarchy.
  • Glücksborg (in full: Slesvig-Holsten-Sønderborg-Glücksborg) dynasty
  • Christian IX S/o Frederick William...................15 Nov 1863 - 29 Jan 1906
  • Growing up as a prince of Schleswig-Holstein-Sonderburg-Glücksburg, a junior branch of the House of Oldenburg which had ruled Denmark since 1448, Christian was originally not in the immediate line of succession to the Danish throne. However, in 1852, Christian was chosen as heir to the Danish monarchy in light of the expected extinction of the senior line of the House of Oldenburg. Upon the death of King Frederick VII of Denmark in 1863, Christian acceded to the throne as the first Danish monarch of the House of Glücksburg. He was Duke of Schleswig, Holstein and Lauenburg 15 November 1863 - 1864. The Second Schleswig War began on 01 February 1864, when Prussian forces crossed the border into Schleswig. Denmark fought Prussia and Austria. Like the First Schleswig War (1848–51), it was fought for control of the duchies of Holstein and Lauenburg due to the succession disputes concerning them when the Danish king died without an heir acceptable to the German Confederation. Decisive controversy arose due to the passing of the November Constitution, which integrated the Duchy of Schleswig into the Danish kingdom in violation of the London Protocol. Reasons for the war were the ethnic controversy in Schleswig and the co-existence of conflicting political systems within the Danish unitary state. The war ended on 30 October 1864, when the Treaty of Vienna caused Denmark's cession of the Duchies of Schleswig, Holstein, and Saxe-Lauenburg to Prussia and Austria.
  • Frederik VIII Frederik Vilhelm Carl..................29 Jan 1906 - 14 May 1912
  • He was the eldest son of Christian IX. Before his accession to the throne at age 63, he served as crown prince for 43 years. During the long reign of his father, he was largely excluded from influence and political power. Frederik VIII's brother Prince Vilhelm [William] become King of Greece (30 March 1863 – 18 March 1913) as George I.
  • Christian X Carl Frederik Albert Alexander Vilhelm..14 May 1912 - 31 Mar 1917
  • He was the eldest son of Frederik VIII and King of Denmark till 20 April 1947. He became the only king of Iceland (where the name was officially spelled Kristján) 01 December 1918 - 17 June 1944. His brother Christian Frederik Carl Georg Valdemar Axel became King Haakon VII of Norway (18 November 1905 − 21 September 1957).
• United States............................................31 Mar 1917 - date
   

• The Rigsdaler = 96 skilling. was the currency of the Danish West Indies (now the U.S. Virgin Islands) until 1849. The Rigsdaler was equal to 4⁄5 Danish rigsdaler. The rigsdaler was replaced by the daler. In 1766 and 1767, 6, 12 and 24 skilling coins were struck in silver for the Danish West Indies. These were followed in 1816 by silver 2, 10 and 20 skilling coins, which were struck until 1848. All the coins carried the wording "Dansk Amerik(ansk) M(ynt)" (Danish American Coinage) to distinguish them from regular Danish coins. The 2 Skillings, Danish coins exported to the Danish West Indies, were minted from old dies in 1805. II skilling (1816, 1837, 1847 and 1848), X skilling (1816, 1840, 1845, 1847 and 1848) and XX skilling (1816, 1840, 1845, 1847 and 1848) are known silver coins from 19th century.
• Some USA coins were countermarked to be used in 1850. The only countermark authorized for the Danish West Indies was the crowned F R VII monogram, which was used to countermark a quantity of US 25 cents and 50 cents coins between March to June 1850. A total face value of $1,140 in U.S. coins. Other coins imported for use during that time  included 1 cent, 5 cents and 10 cents, which were not countermarked. These countermarked coins are been counterfeited extensively. A common counterfeit countermark lacks the small cross on the top of the crown and small shallow striking of c/m especially in beads of crown. Other more deceptive countermarks also have been detected. Extreme care should be taken in ensuring the authenticity of these pieces. 25 cents dated 1849 (10 known) and 50 cents dated 1848 (5 known), 1849 (5 known) and 1850 (6 known) countermarked coin are so far recognized.

• Daler = 5 Francs = 100 cents = 500 bits were introduced from 1904-1917. ½ cent (2½ bits) bronze coin in 1905, 1 cent (5 bits) bronze coins in 1905 and 1913, 2 cents (10 bits) bronze coin in 1905, 5 cents (25 bits) Nickel coin in 1905, 10 cents (50 bits) Silver coin in 1905, 20 cents (Franc) Silver coins in 1905 and 1907, 40 cents (2 Francs) Silver coins on 1905 and 1907, 4 Daler (20 Francs) Gold coins in 1904 and 1905 and 10 Daler (50 Francs) Gold coins in 1904 and 1905 are commonly known.

Since 1917 US Dollars and cents are used in normal circulation.