I think what you're seeing is the consequence of trying to tell the wrong story: a story whose plot we want to hear now, but which wasn't the plot that people cared about at the time.

So you end up with gaps. It's not a very good story, if you try to tell it anyway.

If people are talking about the Cuban Missile Crisis and whether artichokes are too expensive and how Alice's sister is going to move to Chicago after all and the oh!-the-Beatles! and so on, you can't really make the story about race. What do people talk about? All kinds of day-to-day or national or international things that come up and are quickly forgotten; things which are irrelevant to the topic we're trying to talk about now.

I think it would be more honest just to not try to tell the story when the plot isn't there.