 
 <translate> The important part for answering this question is: The islands were purchased from the Danish by the United States in 1917 under the Treaty of the Danish West Indies. So, the answer is 1917. <hau> Muhimmin bangare don amsa wannan tambayar shine: Amurka ta sayi tsibiran daga Danish a 1917 a karkashin Yarjejeniyar Danish West Indies. Saboda haka, amsar ita ce 1917. 