Below is a 6:00 clip showing what 20,000 Nazis look like at a rally at Madison Square Garden celebrating American. It is very scary.
Here's a quote about the film from the Director, Marshall Curry:
The footage is so powerful, it seems amazing that it isn't a stock part of every high school history class. But I think the rally has slipped out of our collective memory in part because it’s scary and embarrassing. It tells a story about our country that we’d prefer to forget. We’d like to think that when Nazism rose up, all Americans were instantly appalled. But while the vast majority of Americans were appalled by the Nazis, there was also a significant group of Americans who were sympathetic to their white supremacist, anti-Semitic message. When you see 20,000 Americans gathering in Madison Square Garden you can be sure that many times that were passively supportive.
In a part of Fritz Kuhn’s speech that isn’t in the film, he applauds Father Coughlin whose radio shows praising Hitler and Mussolini reached audiences of 30 million. Henry Ford and Charles Lindberg expressed anti-Semitic beliefs. And press magnate William Randolph Hearst declared, “Whenever you hear a prominent American called a fascist, you can usually make up your mind that the man is simply a loyal citizen who stands for Americanism.” (In a small ironic twist, we licensed some of the Bund footage from the Hearst collection at UCLA.)
The Image: By Department of Defense. Department of the Army. Office of the Chief Signal Officer. (09/18/1947 – 02/28/1964); ARC Identifier 36068 / Local Identifier 111-OF-2 1943 – public.resource.orgNote: Same image is incorporated in "A Salute to France", American propaganda film to educate US soldiers going to France, Story RG-60.0970, Tape 914at Steven Spielberg Film and Video Archive at USHMM, courtesy of NARA, [http://resources.ushmm.org/film/display/main.php?&file_num=1452 File Num 14, Public Domain, https://commons.wikimedia.org/w/index.php?curid=10212181