Vegetarianism has, of course, existed as a cultic practice for many centuries, but I'm wondering about the rise in popularity/social acceptance of secular vegetarianism in the United States, a nation that especially in the 20th century was known for the aggressive industrialization of the meat industry, and post-war, for the widespread consumption of meat and patriotic zeal for meat-eating as an essential part of being an American. Thanks in advance!
This doesn't directly answer your question, but I would recommend reading The Heretic's Feast by Colin Spencer. It isn't limited to the US but does cover a lot of the history in the US.