Over half of an estimated 100,000 to 500,000 documents accumulated in Russian consulates throughout the U.S. in the late 19th and early 20th century are believed to be case files on Jewish immigrants to the U.S. The documents, left behind when the Russian consulate in the U.S. was closed following the 1917 Russian Revolution, were discovered by chance in the 1970’s at a storage center of the National Archives.