That is actually true.
Surprisingly fiery YouTube video
But the country was further to the left in the 1930s and 1940s than it is today, and there were many Americans even more radical than Katharine Hepburn.
Only in the economic and political senses. Socially and culturally, the country was far more conservative under FDR than it was under Ronald Reagan, much less Donald Trump. The leftism of that time was a completely different animal, however much today's lefties want to claim continuity.
What Communist country, or Left prior to the "new left," supported homosexuality or this "transgender" nonsense? The "western" Left has gone stark-raving mad on causes Karl Marx never imagined. Of course, the fact that Communist countries tend to be socially conservative doesn't bother the hippies any. Their goal is to stick it to the "rednecks," which they do by supporting Communist countries, Black Fundamentalists, islamic theocrats, and homosexuals simultaneously. As I've often remarked, today's Leftist coalition resembles nothing so much as the "heel" dressing room in the days of old-time, "kayfabe" professional wrestling.