Comment by WarOnPrivacy

Some excerpts:

    Over the past few decades, an astonishing pattern has taken place:
    Americans no longer migrate.

    In 1970, one in five Americans was moving every year. 
    It's now down to one in 13.

    For more than 100 years before, my neighborhood had been
    a place for the children of immigrants, for strivers who
    were trying to better their condition.
    Suddenly, it wasn't doing that anymore. It was turning into
    a neighborhood of young professionals.

Unstated here is that nothing replaced that loss.