Why was 1919 such a watershed year for the United States and the world?

DOUBLE SPACED Answer “Why was 1919 such a watershed year for the United States and the world?” You can use some outside sources but at least 3 from the textbook. I will send you pages from the textbook that you can choose and cite. Also it doesn’t matter really how you site (footnotes or bibliography) as long as the professor can clearly tell its cited and I didn’t plagiarize. Also the citation for the textbook is below “Foner, Eric. Give Me Liberty!: An American History (Seagull Fifth Edition) (Vol. 2), 5th Edition. W. W. Norton & Company, 20160915. [Bookshelf Online].”