context: In the year 1940 during World War II the family fled and found a place on a ship bound for the United States leaving France when the German army began to invade the country. Vladimir got a job as a butterfly champion at the American Museum of Natural History in New York for a while but continued to be a lecturer in literature and since 1948 a professor of literature at Cornell University. Since 1945 he was a US citizen.
question: What year did Vladimir Nabokov move to the United States?
answers.text: 1940