Complex sentence: By the mid- 1940s, beanies fell out of popularity as a hat in favor of cotton visored caps like the baseball cap although, in the 1950s and possibly beyond, they were worn by college freshmen and various fraternities as a form of mild hazing.
Split into simpler sentences: By the mid- 1940s, beanies fell out of general popularity as a hat, in favor of cotton visored caps like the baseball cap. However, in the 1950s and possibly beyond, they were worn by college freshmen and various fraternity initiates as a form of mild hazing.