The graph you linked shows that the total fertility rate was nearly 3.7 in 1960 but kept dropping to reach as low as 1.7 in 1976. Afterward it gradually, irregularly went up to reach 2.1 in 2006 and 2007. Since then it has gone down again.
Or to look at a time series covering more history,
the American TFR dropped continuously in the 140 years between 1800 and 1940. But it went up again after 1940 to reach that new local Baby Boom peak in 1960 where your graph starts.
I'm sure there are arguments to believe that "this time it's different" and that fertility won't go up again, but it has dropped and then risen again before.
I feel like 2006-7 was the last hurrah before the financial crisis happened and people lost that optimism that things were going to be ok environmentally and society-wise again where they wanted to have children. I don't know if that is coming back.
But again they were only treading water in 2006-7 and keeping population steady. For it to go above 2.1 and actually increase the population would take something happening that we haven't seen since 1971.
Things are better in many many ways than they were then. We just have a media and a political propaganda industry that runs on rage and fear bait.
The political parties have a vested interest in convincing you that civilization is about to collapse or driving you into a rage because turnout decides elections.
Or to look at a time series covering more history,
https://www.statista.com/statistics/1033027/fertility-rate-u...
the American TFR dropped continuously in the 140 years between 1800 and 1940. But it went up again after 1940 to reach that new local Baby Boom peak in 1960 where your graph starts.
I'm sure there are arguments to believe that "this time it's different" and that fertility won't go up again, but it has dropped and then risen again before.