I think the pendulum swinging from one extreme to the other was most clearly displayed in comparing and contrasting the 1860s and 1920s.
It would be hard to come up with two decades more different. The differences were so great, it's almost like you're talking about two different countries.
For roughly the past ten years, the mood in the U.S. has not been good. The outlook is not very optimistic, IMO, despite that being uncharacteristic of the country. This became more obvious to me when I would visit the Netherlands and then compare what I had experienced there to what I found here. I would hesitate to say more for fear of being political. Yet even if I could, I would not discuss politics here or anywhere else. There aren't many people who despise politics more than I do. That doesn't mean, of course, I believe in avoiding, for instance, the news. I've got a relative who does that. She thinks if she avoids listening to the news then the problems that are discussed might just go away. I was once watching the local news. I went into the kitchen. While I was there, she changed the channel. It's my aunt, BTW. When I got back, I found speed racing which for audio had some inexplicable country music playing. She said "I was afraid that channel you had on was going to start talking about war in the Middle East!!!"