A great insight from a blog I just found.
The Western tradition, informed by the Catholic scholarly traditions, is diachronic and dispassionate. History is a series of events, each influencing the other. The French Revolution, for example, led to Napoleon, the latter being the result of the former.
The Progressive sense of history is synchronic and emotional. The Civil Rights Movement has enormous emotional resonance with the left so it is of constant interest and talked about as if it happened yesterday. On the other hand, the near total domination of America urban centers by Progressive politicians has no emotional resonance so may as well have happened ten thousand years ago or not at all.