Albert Einstein chose to emigrate to the United States because of Adolf Hitler's rise to power. Due to Einstein's Jewish ancestry, he was targeted by Nazis.
Einstein's decision to move came one month before Adolf Hitler took over as the German chancellor. In the years prior to Hitler's takeover, Jews were being targeted by the Nazi movement. Einstein's work in relativity was denounced and made him an even bigger target than his ancestry. In fact, the Nazis enlisted a number of other physicists to refute the findings of Einstein. The result was a published finding entitled "One Hundred Authors Against Einstein." Following a professorship in California, Einstein returned to Germany and renounced his citizenship. His home was later turned into a Nazi youth camp.
Before Einstein left for the United States for good in 1932, a magazine declared that the scientist had "not yet hanged" on its cover. A bounty was placed on his head. When Einstein arrived in the United States, he took a position at the Institute for Advanced Study in New Jersey. He never returned to Germany. When Einstein settled in Princeton, other renowned physicists and other scientists from around the world moved there to study and work with him. Einstein later became an American citizen.