The Simon Wisenthal Center in Los Angeles said it has purchased the four-page letter written by Hitler on Sept. 16, 1919, to a fellow member of the German army, the Los Angeles Times reported.
The center called the letter "one of the most important documents in the history of the Third Reich."
Center dean Rabbi Marvin Hier said the letter illustrates the early roots of Hitler's anti-Semitism.
"In 1919, no one is saying that he was thinking of gassing the Jews; what he was thinking about was the legal removal of Jews from society," Hier said. "Twenty-two years later, he implemented everything that he wrote in that letter."
Hier said the center was approached about a month ago to buy the letter for $150,000. Previously, it was in the hands of private collectors.
He said the letter, along with an English translation, would go on permanent display sometime in July in the center's Holocaust section.
"It belongs in an institution that perpetuates the memory of the Holocaust," Hier said.